ASoC: fsl_xcvr: Revert fix missing lock in fsl_xcvr_mode_put()

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

ASoC: fsl_xcvr: Revert fix missing lock in fsl_xcvr_mode_put()

This reverts commit f51424872760 ("ASoC: fsl_xcvr: fix missing lock in fsl_xcvr_mode_put()").

The original patch attempted to acquire the card->controls_rwsem lock in
fsl_xcvr_mode_put(). However, this function is called from the upper ALSA
core function snd_ctl_elem_write(), which already holds the write lock on
controls_rwsem for the whole put operation. So there is no need to simply
hold the lock for fsl_xcvr_activate_ctl() again.

Acquiring the read lock while holding the write lock in the same thread
results in a deadlock and a hung task, as reported by Alexander Stein.