msm: kgsl: Modify dispatcher to accept generic objects

Currently dispatcher accepts kgsl_cmdbatch object. This object
is a superset of all the types of objects dispatcher accepts.
Split kgsl_cmdbatch object to SYNC and IB/MARKER objects and
structure the code to make it easier for new type of objects
to be added to the dispatcher queue.

CRs-Fixed: 1054354
Change-Id: I2d482d1081ce6fdb7925243c88ce00ea6b864efe
Signed-off-by: Tarun Karra <tkarra@codeaurora.org>