treewide: Add missing includes ...

A lot of files rely on include/driver.h including include/of.h (and
this including include/errno.h. include the files explicitly so we can
eventually get rid of including of.h from driver.h

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

memory_display: Change address pointer to type const void * ...

No need to force a width of the pointer, so use void *. Also it's
not modified in memory_display, so also add a const.

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

memory commands: move memory_display to separate file ...

memory_display is a function which should generally be available.
Currently it depends on memory command support being compiled in,
so move the function to a separate file.

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