defconfig: msm: Enable marking free pages as readonly option

FREE_PAGES_RDONLY debug feature helps to mark the pages
as read only after they are freed and helps to catch the
corruption at source in some scenarios.

Change-Id: I3d9d4fb35871c3afce5b8099de006a20be980607
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>