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

ARMv7-A:  Map all of .text, .bss, .data., stacks before enabling the MMU and caching. This is simpler and avoids fears I have about caching

ARMv7-A:  Separate CONFIG_PAGING start-up logic into a different startup file.  Too much conditional compilation.

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