block: Make request_queue.rpm_status an enum

request_queue.rpm_status is assigned values of the rpm_status enum only,
so reflect that in its type.

Note that including <linux/pm.h> is (currently) a no-op, as it is
already included through <linux/genhd.h> and <linux/device.h>, but it is
better to play it safe.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/blkdev.h

@@ -24,6 +24,7 @@
 #include <linux/percpu-refcount.h>
 #include <linux/scatterlist.h>
 #include <linux/blkzoned.h>
+#include <linux/pm.h>
 
 struct module;
 struct scsi_ioctl_command;
@@ -458,7 +459,7 @@ struct request_queue {
 
 #ifdef CONFIG_PM
 	struct device		*dev;
-	int			rpm_status;
+	enum rpm_status		rpm_status;
 	unsigned int		nr_pending;
 #endif