slimbus: slim-msm: Handle system suspend while active slimbus transfers

If system suspend happens during active slimbus transfers
or before runtime pm suspend, return error so that system
suspend gets abort and re-runs after slimbus finishes
transfers or rutime pm calls execution.

Change-Id: Icf355f162fd1a69c35565c31aa478c4987932b39
Signed-off-by: Dilip Kota <dkota@codeaurora.org>