msm: kgsl: Do not overvote for GMU ddr bandwidth

Restrict initial GMU BW vote to minimum vote for
wake up powerlevel. Do not use default vote as it can
be excessive.

Change-Id: Id29e489be41204b7d1f2822d040118ac3dfb2233
Signed-off-by: Oleg Perelet <operelet@codeaurora.org>