msm: kgsl: Pare down the gmu core and dev ops

Remove the ones that we don't need anymore. Also, remove
KGSL_STATE_RESET as it was only needed with gmu recovery, which
now is completely target specific. Also, remove unused adreno gmu
register defines.

Change-Id: I20b8bc04714e30cd7418d81e8634e4c5079fa175
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>