Revert "ALSA: timer: fix NULL pointer dereference in read()/ioctl() race"

The patch "BACKPORT: ALSA: timer: Fix race between read and ioctl" is
picked from kernel_msm, however linux-stable had
cd0365e75073414886d0be26260b1dd00de9863c but Google did not.
Thus, when we picked that, an unbalanced lock occurred.

Fix that by removing depulicate ioctl_lock, or we will see a clear
deadlock as there is another same lock already being held.

This reverts commit cd0365e75073414886d0be26260b1dd00de9863c.

Change-Id: I0c6d13099de9d76cd799f9c00b19ad238c56043d