Fix bad ThrottleDevice path

Fixes moby/moby#44904.

Signed-off-by: Albin Kerouanton <albinker@gmail.com>

opts/throttledevice.go

@@ -31,7 +31,7 @@ func ValidateThrottleBpsDevice(val string) (*blkiodev.ThrottleDevice, error) {
 	}
 
 	return &blkiodev.ThrottleDevice{
-		Path: v,
+		Path: k,
 		Rate: uint64(rate),
 	}, nil
 }