clk: remove duplicated code with __clk_set_parent_after

__clk_set_parent_after() actually used the second argument then we
could put this duplicate logic in there and call it with a different
order of arguments in the success vs. error paths in this function.

Cc: Mike Turquette <mturquette@linaro.org>
Suggested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Dong Aisheng <aisheng.dong@freescale.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>