msm: kgsl: Fix nice level for higher priority GPU start thread

Before, we were actually setting the lowest possible priority.

Change-Id: I3a52de949eee0faea8061dd91ed303fa8231f0d4

Signed-off-by: flar2 <asegaert@gmail.com>
msm: kgsl: Schedule adreno_start in a high priority workqueue

Better safe than sorry. Also, return early if we didn't set a _wake_timeout.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>