Experimental change to STM32 Ethernet driver a success.  Porting change to all other Ethernet drivers.

Implements support for smaller interrupt tables as described at http://www.nuttx.org/doku.php?id=wiki:howtos:smallvectors .  This is largely the work of Mark Schulte.  However, I have made several changes to match with the Wiki document.  If you like the change, thanks go to Marc.  For any errors you can blame me.

Revert "CONFIG_START_YEAR/MONTH/DAY not required if an RTC is used"

Approved-by: Gregory Nutt

This reverts commit 4035ed8c.

stm32_gpiosetevent: GPIO IRQ function should not return the xcpt_t oldhandler.  This value is useful and potentially dangerous by itself after the change to assocaite a argument with the interrupt handler.

stm32_gpiosetevent: GPIO IRQ function should not return the xcpt_t oldhandler.  This value is useful and potentially dangerous by itself after the change to assocaite a argument with the interrupt handler.

stm32_gpiosetevent: GPIO IRQ logic no longer returns the xcpt_t oldhandler.  This value is useless and dangerous after the recent changes to interrupt argument passing.

board_button_irq: Button IRQ logic no longer returns the xcpt_t oldhandler.  There value is useless and dangerous after the recent changes to interrupt argument passing.

board_button_irq: Button IRQ logic no longer returns the xcpt_t oldhandler.  There value is useless and dangerous after the recent changes to interrupt argument passing.

board_button_irq: Button IRQ logic no longer returns the xcpt_t oldhandler.  There value is useless and dangerous after the recent changes to interrupt argument passing.

Tiva: Pin IRQ logic no longer returns the xcpt_t oldhandler.  There value is useless and dangerous after the recent changes to interrupt argument passing.

STM32 L4: Pin IRQ logic no longer returns the xcpt_t oldhandler.  There value is useless and dangerous after the recent changes to interrupt argument passing.

PIC32MZ: Pin IRQ logic no longer returns the xcpt_t oldhandler.  There value is useless and dangerous after the recent changes to interrupt argument passing.

PIC32MX: Pin IRQ logic no longer returns the xcpt_t oldhandler.  There value is useless and dangerous after the recent changes to interrupt argument passing.

Kinetis-L GPIO: Pin IRQ logic no longer returns the xcpt_t oldhandler.  There value is useless and dangerous after the recent changes to interrupt argument passing.

STM32 Ethernet: Need two work structures so that pending poll work is not lost when an interrupt occurs.

Kinetis GPIO: Pin IRQ logic no longer returns the xcpt_t oldhandler.  There value is useless and dangerous after the recent changes to interrupt argument passing.

STM32/F7/L4: EXTI ALARM function no longer returns the xcpt_t oldhandler.  There value is useless and dangerous after the recent changes to interrupt argument passing.

STM3 L4: EXTI COMP function no longer returns the xcpt_t oldhandler.  There value is useless and dangerous after the recent changes to interrupt argument passing.

STM32/F7/L4: EXOT PVD function no longer returns the xcpt_t oldhandler.  There value is useless and dangerous after the recent changes to interrupt argument passing.

arch_phy_irq:  Now returns int instead of xcpt_t oldhandler.  The oldhandler is useless after the changes to the interrupt argument.  Also access an argument for the PHY interrupt.  phy_notify.c driver changed to exploit new interrupt argument passing.

configs/: All functions that used to return an xcpt_t old handler value, not return NULL.  The oldhandler value is no longer useful with the recent changes to the interrupt argument passing.

Remove unused variable

Approved-by: Gregory Nutt