msm: kgsl: GPU pagefault policy change to not stall on pagefault

GPU pagefault policy is changed to not stall on pagefault, most
of the time GPU pagefault is harmless and stalling for every
pagefault is not required on a commercial device. Sysfs option
to stall on pagefault exists for developers to debug pagefault.

Change-Id: Iecdcc2d57f09a56a2d4830943616702426d3d83e
Signed-off-by: Tarun Karra <tkarra@codeaurora.org>