sfp: fix sparse warning

drivers/net/phy/sfp-bus.c:298:13: warning: context imbalance in 'sfp_bus_release' - wrong count at exit
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/sfp-bus.c

@@ -291,7 +291,7 @@ static struct sfp_bus *sfp_bus_get(struct device_node *np)
 	return found;
 }
 
-static void sfp_bus_release(struct kref *kref) __releases(sfp_mutex)
+static void sfp_bus_release(struct kref *kref)
 {
 	struct sfp_bus *bus = container_of(kref, struct sfp_bus, kref);