ASoc: rockchip: i2s: Fix RPM imbalance

If rockchip_pcm_platform_register() fails, e.g. upon deferring to wait
for an absent DMA channel, we return without disabling RPM, which makes
subsequent re-probe attempts scream with errors about the unbalanced
enable. Don't do that.

Fixes: ebb75c0b

 ("ASoC: rockchip: i2s: Adjust devm usage")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/bcb12a849a05437fb18372bc7536c649b94bdf07.1570029862.git.robin.murphy@arm.com


Signed-off-by: Mark Brown <broonie@kernel.org>