ASoC: rockchip: i2s: fix unbalanced clk_disable

mclk is enabled and disabled only in i2s_runtime_{resume,suspend}() and
we ensure that the device is runtime suspended before reaching this
clk_disable_unprepare() call, so it is wrong to call it again here.

Signed-off-by: John Keeping <john@metanate.com>
Signed-off-by: Mark Brown <broonie@kernel.org>