msm: kgsl: Don't call del_timer_sync() with spinlock

If timer handler is executing on another core and
del_timer_sync() is called then it waits for the timer
handler to finish executing. Calling this function while
holding a lock which the timer handler might also need can
lead to a deadlock.

CRs-Fixed: 883016
Change-Id: Ibb408d403f1252a184f331bb5798e85df097f6bc
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>