msm: kgsl: Return supported page size based on available memory pools

In case memory pools are supported return the page size as
supported only if corresponding memory pool is available.
This will increase the usage of memory pool and will reduce the
overall allocation time.

Change-Id: Iea84a4259b38fe9cb546419dfcbaf0a9666e7ca9
Signed-off-by: Deepak Kumar <dkumar@codeaurora.org>