scsi: smartpqi: mark PM functions as __maybe_unused

The newly added suspend/resume support causes harmless warnings when
CONFIG_PM is disabled:

smartpqi/smartpqi_init.c:5147:12: error: 'pqi_ctrl_wait_for_pending_io' defined but not used [-Werror=unused-function]
smartpqi/smartpqi_init.c:2019:13: error: 'pqi_wait_until_lun_reset_finished' defined but not used [-Werror=unused-function]
smartpqi/smartpqi_init.c:2013:13: error: 'pqi_wait_until_scan_finished' defined but not used [-Werror=unused-function]

We can avoid the warnings by removing the #ifdef around the handlers and
instead marking them as __maybe_unused, which will let gcc drop the
unused code silently.

Fixes: f44d210312a6 ("scsi: smartpqi: add suspend and resume support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>