msm: kgsl: Fix NULL pointer dereference of of_match_device()

There is a posibility that of_match_device() can return NULL
and can be dereferenced. To avoid this, a safety check is added
in adreno_probe() and adreno_remove().

Change-Id: I7fb68db3cd4f898d87d07f2434fb7c9ce2f4e7e5
Signed-off-by: Sravankumar bijili <csbijil@codeaurora.org>