arm: remove support for non-standard memory tags

In older versions, there were memory tags that represented
memory which could be hotplugged, memory which could be
put into self-refresh and memory which could be reclaimed
from OSBL. The last of these was never implemented and
due to a re-architecting of the way DMM determines which
memory can be hotplugged, the other two tags are no longer necessary.

Signed-off-by: Larry Bassel <lbassel@codeaurora.org>

Conflicts:

	arch/arm/mm/init.c