clk: qcom: clock-generic: Correct error path for mux_div set rate

Currently, when enabling the new_parent of a mux_div clock fails,
we do not set the new_parent back to it's original rate. Fix that.

Change-Id: I599d0ae35a4336b0b84320933540b35d76af6369
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>