msm: kgsl: Don't repeatedly call adreno_stop during reset

The driver attempts GPU reset several times if the first attempt
fails.  If adreno_start() fails it will clean itself up and turn
off the GPU so there is no reason to call adreno_stop again. In
fact, it is dangerous to do so as adreno_stop makes the assumption
that the GPU is on.

Change-Id: Ic0dedbad00aad38bad6b532f1a3266e0cad22352
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>