Add ENCX24J600 Ethernet driver and support for the ENCX24J600 with the Olimex STM32 P107 board.  From Max Holtberg

SAMA5: EHCI now handles low- and full-speed connections by giving them to OHCI; OHCI now uses the work queue to defer interrupt processing; If both OHCI and EHCI are enabled, EHCI is the master of the UHPHS interrupt

SAMA5 OHCI:  Re-organize some endpoint list data structures.. Strange things happen when semaphores lie in DMA memory which is occasionally invalidated

SAMA5:  Alternatie clock configuration that yields a perfect 48MHz full speed USB clock and a CPU clock of 384MHz

Clean up some LP17xx and STM32 USB host configuration compilation errors due to the massive changes to the USB host interfaces needed to support the SAMA5

Separate wait() and enumerate() methods from struct usbhost_driver_s and move to new interface, struct usbhost_connection_s.  This is part of the necessary restructuring of the USB host interface to support multiple root hub ports.

Add untested OHCI driver for the SAMA5; structure naming and header files for USB host initialization prototypes

SAMA5: Add PIO interrupt support.  Massive name changes for consistency in PIO vs GPIO naming.  SAMA5D3x-EK:  Add support for SD card detection PIO interrupts

SAMA5:  SPI Driver + AT25 FLASH work; SAM3/4:  Correct an error, SPI will not be correctly configured if CONFIG_SPI_OWNBUS=n

Standard configuration variables used to enable interupt controller debug; SAMA5: Correct handling of spurious interrupts