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: I72a3a3c7b5fdafb29bbd7164c59e439a029c61f6
Signed-off-by: Jilai Wang <jilaiw@codeaurora.org>