SAMA5:  When booting from SDRAM, don't copy vectors to ISRAM.  Instread just set the VBAR register to add address of the vectors in SDRAM

If LOWVECTORS is selected, then we need to clear the VBAR register.  A bootloader may have left the VBAR in an bad state

SAMA5: Make sure the MMU and caches are disabled on power up; flush the vector region D-Cache after copying interrupt vectors; make sure that D-Cache, I-Cache, and TLBs are invalidated after modifying the AXI MATRIX remapping

sscanf(): Was returning the wrong number of conversions in many cases; Also, needs to return EOF if there were no conversions

SAMA5D3x-EK: Change name of all board-specific configuration variables so that there are no collisions with names of similar variables for other boards