intel_scu_ipc: remove PM command synchronization

intel_scu_ipc: remove PM command synchronization

BZ: 32160

In R2 we had added serialization of IPC and PM (s0ix/lpmp3/d0ix) commands
since there were fabric errors, those issues were root caused and fixed in
SCU hence we no longer require this synchronization.

Also adding synchronization may adversly affect IPC communication, since
WatchDog keepalive is sent thru and IPC command and if s0ix is in progress the
watchdog keep alive timer may get blocked till the s0ix command gets completed
and this could take couple of seconds, by which time watch dog could get
triggerred.

Hence removing this synchronization.

Change-Id: I52b91d5c84ee8cc380d13f63cc46fa2017e4e4f2
Signed-off-by: Illyas Mansoor <illyas.mansoor@intel.com>
Reviewed-on: http://android.intel.com:8080/43669
Reviewed-by: Martin, LoicX <loicx.martin@intel.com>
Tested-by: Martin, LoicX <loicx.martin@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>