scsi: raid_attrs: fix unused variable warning

I ran into a new warning on randconfig kernels:

drivers/scsi/raid_class.c: In function 'raid_match':
drivers/scsi/raid_class.c:64:24: error: unused variable 'i' [-Werror=unused-variable]

This looks like a very old problem that for some reason was very hard to
run into, but it is very easy to fix, by replacing the incorrect #ifdef
with a simpler IS_ENABLED() check.

Fixes: fac829fdcaf4 ("[SCSI] raid_attrs: fix dependency problems")
Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/raid_class.c

···
 	 * emulated RAID devices, so start with SCSI */
 	struct raid_internal *i = ac_to_raid_internal(cont);
 
-#if defined(CONFIG_SCSI) || defined(CONFIG_SCSI_MODULE)
-	if (scsi_is_sdev_device(dev)) {
+	if (IS_ENABLED(CONFIG_SCSI) && scsi_is_sdev_device(dev)) {
 		struct scsi_device *sdev = to_scsi_device(dev);
 
 		if (i->f->cookie != sdev->host->hostt)
···
 
 		return i->f->is_raid(dev);
 	}
-#endif
 	/* FIXME: look at other subsystems too */
 	return 0;
 }