net/phy/fixed.c: fix a use-after-free

This patch fixes a use-after-free introduced by
commit a79d8e93d300adb84cccc38ac396cfb118c238ad and spotted by the
Coverity checker.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/phy/fixed.c

@@ -236,12 +236,12 @@ module_init(fixed_mdio_bus_init);
 static void __exit fixed_mdio_bus_exit(void)
 {
 	struct fixed_mdio_bus *fmb = &platform_fmb;
-	struct fixed_phy *fp;
+	struct fixed_phy *fp, *tmp;
 
 	mdiobus_unregister(&fmb->mii_bus);
 	platform_device_unregister(pdev);
 
-	list_for_each_entry(fp, &fmb->phys, node) {
+	list_for_each_entry_safe(fp, tmp, &fmb->phys, node) {
 		list_del(&fp->node);
 		kfree(fp);
 	}