msm: kgsl: Add WQ_SYSFS to the worker threads

Add WQ_SYSFS to the worker threads so that they show
up under /sys/bus/workqueue/devices.  This allows some
of the properties to be adjusted at runtime.

Change-Id: I3424ae51461e04e0771560ff1c5b35cdf5b1fd6c
Signed-off-by: Jonathan Wicks <jwicks@codeaurora.org>