In SKL+ platforms, all IPC commands are serialised, i.e. the driver sends
a new IPC to DSP, only after receiving a reply from the firmware for the
current IPC.

Hence it seems apparent that there is only a single modifier of the IPC RX
List. However, during an IPC timeout case in a multithreaded environment,
there is a possibility of the list element being deleted two times if not
properly protected.

So, use spin lock save/restore to prevent rx_list corruption.
Signed-off-by: Pardha Saradhi K <pardha.saradhi.kesapragada@intel.com>
Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty@intel.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>