defconfig: msm: Enable FREE_PAGES_RDONLY config flag

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: I6ceee20d2f0360d7ff8fb0b361de39fa4058d5c1
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>