msm: acpuclock-8226: Use gpll0 during power collapse.

Change the source used while going into power collapse to gpll0. This
also requires gpll0 to be always on when linux is on, since clocks
cannot be prepared/unprepared in the atomic power collapse path.

Change-Id: Id4beb86df6e5310ab8d6b2aca5209fa7d3ede475
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>