SAMV7: Add framework for USB DCD.  Initial check-in is just the SAMA5 USB DCD with naming changes to get a clean compilation.  Needs careful review and comparison with datasheet and, of course, testing

Update some recent Tiva changes so that old LM3S parts at least still build (but have not been retested)

instead of Kconfig to help reduce bloat and confusion.
- Timer changed to remove ADC coupling in Kconfig to code and moved
configuration up from arch/arm/src/tiva to configs/tm4c123g-launchpad/src.
- GPIO driver needed small fixes in the configuration routines and
discovered false-positive bugs in interrupt testing: interrupts are now
verified to actually be working reliably.
- Attempt to apply some consistency in the tiva arch/ level's interface
to the config/board/ level driver configuration.

From Calvin Maguranis

SAMV7:  Add a sneak internal interface that will allow us to set the MAC address before NSH even starts

SAMV7: Updates to Ethernet driver based on comparison with Atmel sample code.  Add configuration for other PHY GPIOs.  Still no Ethernet interrupts

PIC32MZ: Changes that will permit building of the PIC32MZ Start Kit configuration using MPLAB and the XC32 toolchain.  From David Sidrane

SAMV7: Quick'n'dirty port of the SAMA5D4 Ethernet MAC driver to the SAMV7.  Still some unresovled issues with DCache handling