ASoC: sun4i-codec: pass through clk_set_rate error

The current code, disregarding the clk_set_rate error code, was always
returning -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>