ASoC: stm32: sai: fix OF node leak on probe

In the Linux kernel, the following vulnerability has been resolved:

ASoC: stm32: sai: fix OF node leak on probe

The reference taken to the sync provider OF node when probing the

platform device is currently only dropped if the set_sync() callback

fails during DAI probe.

Make sure to drop the reference on platform probe failures (e.g. probe

deferral) and on driver unbind.

This also avoids a potential use-after-free in case the DAI is ever

reprobed without first rebinding the platform driver.