mm: Don't use CMA page for file cache

Despite the best efforts of redirection, the file system may still
allocate CMA pages with references held for long periods of time.
If a CMA page ends up being allocated, free it and get a non-CMA page.

Change-Id: I2001151a2936a6d0780d223dda85a87c04ddb8c6
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>