zram: kill unused zram_get_num_devices()

Now there's no caller of zram_get_num_devices(), so kill it.
And change zram_devices to static because it's only used in zram_drv.c.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/zram/zram_drv.c

@@ -37,7 +37,7 @@
 
 /* Globals */
 static int zram_major;
-struct zram *zram_devices;
+static struct zram *zram_devices;
 
 /* Module params (documentation at end) */
 static unsigned int num_devices = 1;
@@ -679,11 +679,6 @@ static void destroy_device(struct zram *zram)
 		blk_cleanup_queue(zram->queue);
 }
 
-unsigned int zram_get_num_devices(void)
-{
-	return num_devices;
-}
-
 static int __init zram_init(void)
 {
 	int ret, dev_id;

drivers/staging/zram/zram_drv.h

@@ -110,8 +110,6 @@ struct zram {
 	struct zram_stats stats;
 };
 
-extern struct zram *zram_devices;
-unsigned int zram_get_num_devices(void);
 #ifdef CONFIG_SYSFS
 extern struct attribute_group zram_disk_attr_group;
 #endif