clk: qcom: clk-branch: Correct the round_rate callback behavior

Currently, during a set_rate() operation, the call never makes
its way to the branch clocks parent since the parent_rate is
not updated and matches the stashed rate value of the parent.
Once the parent_rate is updated, the set_rate() call on the
branch clock makes it's way upto the clock parent.

Change-Id: I49c2fc26a13df4c93764f786bc42f5a8e18859fc
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>