defconfig: msm8916: Disable CONFIG_FREE_PAGES_RDONLY

The debug feature was meant to be enabled during stability
period hence disable CONFIG_FREE_PAGES_RDONLY now from both
msm8916-512mb_defconfig and msm8916_defconfig.

CRs-fixed: 683354
Change-Id: Id9d397eef401493d0145b96a0a0da158594ba4af
Signed-off-by: Shiraz Hashim <shashim@codeaurora.org>