msm: npu: Don't wait for SHUTDOWN irq if NPU is not in FPC mode

If NPU fails to enter FPC mode due to watchdog or other errors,
don't wait for SHUTDOWN irq since it won't be triggered.

Change-Id: I87279696ba8bfeabf621507c9795392b171c8455
Signed-off-by: Da Hoon Pyun <dpyun@codeaurora.org>