ASoC: sun4i-codec: pass through clk_set_rate error

Commit 1fb34b48 ('ASoC: sun4i: Implement MIC1 capture') added back some
code that disregards the clk_set_rate error code and always returns
-EINVAL. Fix that and return the code in order to have more clue about
what's going on.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>