clock-gcc-8994: Add MSS_GPLL0 gate clock

MSS needs to vote for GPLL0 before its output can reach MSS clock
controller. Model this vote bit as gate clock.

Change-Id: Ia13ed3847597ac757734cad9ff62a982c61ef91f
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>