Clean up pointer handling to make code more readability.  This re-introduces the compiler optimization problem but this is the correct thing to do.  I will have to drop back from -Os to -O2.

SAMV7 EMAC: Fix alignment issue: RX buffers need to be invalidated.  This means the alignment of buffers must be at least to the data cache line size at both ends of the buffer

SAMV7 EMAC: Sometimes TX is not started when TSTART is set??? Workaround seems to be to set it twice.  Restored full optimization.  Also CONFIG_NET_NOINTS is set so that interrupt level provessing is avoided

SAMV7 USB: Move clock initialization back to sam_clockconfig.c; add seperate UTMI register definition header file; fix a couple of typo bugs

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