msm: kgsl: Remove the extra recovery hop

Currently, when we try to boot the gmu and it fails,
we force off the gmu gdsc followed by an inline
attempt to boot the gmu again. To do this, we go an
extra mile to do complex snapshot and power state
magic.

The same goal can be achieved by a simpler and
easier to maintain code path:

Set the state to KGSL_STATE_RESET upon gmu boot failure
so that the error path performs a RESET -> SLUMBER
transition. Here, we can reset the GMU so that next
SLUMBER exit can start afresh.

Change-Id: I4d3e75f40062e9fe5d71fe1e6010dfff75e09321
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>