clk: Missing set_phase op is an error

If a clock's clk_ops doesn't have the set_phase op set we should
return an error from clk_set_phase(). This way clock consumers
know that when they tried to set a phase it didn't work, as
opposed to the current behavior where the return value is 0
meaning success.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Michael Turquette <mturquette@linaro.org>