btrfs-progs: Fix 'btrfs device stats --check' cli option

"Bug 194961 - btrfs device stats --check <folder> does not work"

The long option --check is not recognized as it's missing from the
option table.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=194961
Reported-by: Tomas Thiemel<thiemel@centrum.cz>
Signed-off-by: Lakshmipathi.G <Lakshmipathi.G@giis.co.in>
Signed-off-by: David Sterba <dsterba@suse.com>

cmds-device.c

@@ -400,6 +400,7 @@ static int cmd_device_stats(int argc, char **argv)
 	while (1) {
 		int c;
 		static const struct option long_options[] = {
+			{"check", no_argument, NULL, 'c'},
 			{"reset", no_argument, NULL, 'z'},
 			{NULL, 0, NULL, 0}
 		};