msm: kgsl: Correctly check if kobj has been initialized

Correctly check if kobject has been initialized by checking
for the ktype member pointer inside kobj struct. If this pointer is
NULL, it clearly indicates that this kobj was not initialized.

Change-Id: I24190f94ec7d3cf39d52366fef8cae3d2f4f0d55
Signed-off-by: Harsh Vardhan Dwivedi <hdwivedi@codeaurora.org>