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

SAMA5: Change mapping of vector tables to work around that fact that I don't understand how the AXI MATRIX remap works

ARMv7-A:  Add cp15_disable_dcache(); SAMA5: nor_main.c no disables MMU and caches; Should not remap ISRAM to address 0x0 unless we booted into ISRAM

SAMA5: The ostest configuration have been converted to run out of NOR flash.  There is more to be done, however