ALSA: compress: use mutex in drain

Since we do not have lock over the function, we need to acquire mutex
when checking and modifying states in drain and partial_drain handlers

Change-Id: I3f8af90a226b772492fb6e09c625ebedc8ebfeb5
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Eric Laurent <elaurent@google.com>
Git-commit: bab68b886fb87ee82a3e7d86d54f7eaa025950ef
Git-repo: https://android.googlesource.com/kernel/msm


Signed-off-by: Dhananjay Kumar <dhakumar@codeaurora.org>
[bgoswami@codeaurora.org: resolved merge conflicts]
Signed-off-by: Banajit Goswami <bgoswami@codeaurora.org>
Signed-off-by: Meng Wang <mwang@codeaurora.org>