ARM: dts: msm: Enable GPU idle power features for MSM8996

Program the deep-nap-timeout to 20 msec to remove the pmqos vote.
Also enable active-only bus voting which releases bus votes when
CPU subsystem is inactive.

Change-Id: I62bf28f23d6116b617bf293607976438b0076e7d
Signed-off-by: Suman Tatiraju <sumant@codeaurora.org>