ASoC: fsl_sai: Fix exiting path on probing failure

If the imx-sdma driver is built as a module, the fsl-sai device doesn't
disable on probing failure, which causes the warning in the next probing:

==================================================================
fsl-sai 308a0000.sai: Unbalanced pm_runtime_enable!
fsl-sai 308a0000.sai: Unbalanced pm_runtime_enable!
fsl-sai 308a0000.sai: Unbalanced pm_runtime_enable!
fsl-sai 308a0000.sai: Unbalanced pm_runtime_enable!
fsl-sai 308a0000.sai: Unbalanced pm_runtime_enable!
fsl-sai 308a0000.sai: Unbalanced pm_runtime_enable!
==================================================================

Disabling the device properly fixes the issue.

Fixes: 812ad463

 ("ASoC: fsl_sai: Add support for runtime pm")
Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Link: https://lore.kernel.org/r/20200205160436.3813642-1-oleksandr.suvorov@toradex.com
Signed-off-by: Mark Brown <broonie@kernel.org>