SAMA5: Add ADC-side of the logic to hook in timer/counter logic needed to drive  periodic ADC sampling

SAMA5:  Hook RTC into build system; Finish RTC alarm logic; Verify correct behavior of the basic RTC functionality

SAMA5 LCD:  Move framebuffers to center of free memory region.  That creates a guard band around the framebuffers that gives a little protection from any bad writes into the framebuffer