scsi: hisi_sas: Work around build failure in suspend function

The suspend/resume functions in this driver seem to have multiple problems,
the latest one just got introduced by a bugfix:

drivers/scsi/hisi_sas/hisi_sas_v3_hw.c: In function '_suspend_v3_hw':
drivers/scsi/hisi_sas/hisi_sas_v3_hw.c:5142:39: error: 'struct dev_pm_info' has no member named 'usage_count'
 5142 |         if (atomic_read(&device->power.usage_count)) {
drivers/scsi/hisi_sas/hisi_sas_v3_hw.c: In function '_suspend_v3_hw':
drivers/scsi/hisi_sas/hisi_sas_v3_hw.c:5142:39: error: 'struct dev_pm_info' has no member named 'usage_count'
 5142 |         if (atomic_read(&device->power.usage_count)) {

As far as I can tell, the 'usage_count' is not meant to be accessed by
device drivers at all, though I don't know what the driver is supposed to
do instead.

Another problem is the use of the deprecated UNIVERSAL_DEV_PM_OPS(), and
marking functions as __maybe_unused to avoid warnings about unused
functions.  This should probably be changed to using
DEFINE_RUNTIME_DEV_PM_OPS().

Both changes require actually understanding what the driver needs to do,
and being able to test this, so instead here is the simplest patch to make
it pass the randconfig builds instead.

Fixes: e368d38 ("scsi: hisi_sas: Exit suspend state when usage count is greater than 0")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20230405083611.3376739-1-arnd@kernel.org
Reviewed-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: arndb

drivers/scsi/hisi_sas/hisi_sas_v3_hw.c

@@ -5139,11 +5139,13 @@ static int _suspend_v3_hw(struct device *device)
 	flush_workqueue(hisi_hba->wq);
 	interrupt_disable_v3_hw(hisi_hba);
 
+#ifdef CONFIG_PM
 	if (atomic_read(&device->power.usage_count)) {
 		dev_err(dev, "PM suspend: host status cannot be suspended\n");
 		rc = -EBUSY;
 		goto err_out;
 	}
+#endif
 
 	rc = disable_host_v3_hw(hisi_hba);
 	if (rc) {
@@ -5162,7 +5164,9 @@ static int _suspend_v3_hw(struct device *device)
 
 err_out_recover_host:
 	enable_host_v3_hw(hisi_hba);
+#ifdef CONFIG_PM
 err_out:
+#endif
 	interrupt_enable_v3_hw(hisi_hba);
 	clear_bit(HISI_SAS_REJECT_CMD_BIT, &hisi_hba->flags);
 	clear_bit(HISI_SAS_RESETTING_BIT, &hisi_hba->flags);