msm: clock-8226: Move set_rate call after handoff

A rcg will get stuck during an update operation if a branch is enabled and
the new parent is off. Since mmpll0 is not guaranteed to always be on, it
is not safe to set the axi_clk_src to use mmpll0 before handoff.

Change-Id: I3503fb4ef00d46148c27c1990e38388aeb38b6e2
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>