msm: remove obsolete DMM code and config options

DMM is no longer supported, but there were still fragments
of the DMM support dependent on the obsolete config options
CONFIG_ENABLE_DMM and CONFIG_FIX_MOVABLE_ZONE present.
Remove these config options and the associated code.

Change-Id: I01c715c8d9c65eebc7ff123a8a0878166b606e0c
CRs-fixed: 460735
Signed-off-by: Larry Bassel <lbassel@codeaurora.org>