msm: kgsl: Correctly change the pagefault policy via sysfs

The pagefault halt policy was not actually taking effect when set
from the sysfs file. Pass in the new policy where required.

Change-Id: I09d557ba3554cb413520d9ff97ac8e68b9b1fd7e
Signed-off-by: Lynus Vaz <lvaz@codeaurora.org>