msm: kgsl: Add check for NULL value from dev_get_drvdata

Check to see if dev_get_drvdata returns NULL and handle it.

CRs-Fixed: 552580
Change-Id: Ic0dedbad426dbbe15896608213067ee7337f3b34
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
driver: staging: prima: updated 3.2.3.172 (70ee632)

dcd84b2 Fix for wifi can not connect networks after wake up
c5a2283 wlan: stop traffic timer during wlan driver shutdown.

Change-Id: I268a9bb9ed9a355baaed2f7946c1cd6b0f580077