msm: kgsl: Don't enable GPU 64bit when kernel is in 32bit configuration

Setting the GPU to 64bit when rest of world is in 32bit can
make the GPU misbehave. Hence, check the kernel configuration
before actually moving the GPU to 64bit mode.

Change-Id: Ie4cf6c2d4fdfa978287c86812bdce4bf8c56ef5f
Signed-off-by: Rajesh Kemisetti <rajeshk@codeaurora.org>