This adds the missing pieces for:

d8a6e1c ARM/mem: handle data aborts gracefully for md

When possible use memmap and directly and dereference the input pointer
directly in memory_display() so that the data abort occurs where we expect
it and not in the md command. With this d8a6e1c can work as expected.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>