msm: kgsl: Remove redundant register write

The interrupt for the message queue is already
being enabled in the interrupt mask for the gmu,
along with other hfi interrupts.

Change-Id: I5a3c8dad67ab0a9e5f305dc24c037242bc4ba22b
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>