clk: msm: clock: Make an RPM request before voting for MIN_SVS on VDD_GFX

As part of a hardware workaround on msm8996, make an RPM request
everytime the clock driver votes for VDD_GFX to go to MIN_SVS.
RPM then caps the max gcc_bimc_gfx_clk frequency based on this
request. Clear the request when the vote for VDD_GFX goes above
MIN_SVS.

Change-Id: I5bd0193692077c6eb9c793bc4deb7694889272d9
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>