of: of_mdio: Correct loop scanning logic

Commit 209c65b61d94 ("drivers/of/of_mdio.c:fix of_mdiobus_register()")
introduced a break of the loop on the premise that a successful
registration should exit the loop. The premise is correct but not to
code, because rc && rc != -ENODEV is just a special error condition,
that means we would exit the loop even with rc == -ENODEV which is
absolutely not correct since this is the error code to indicate to the
MDIO bus layer that scanning should continue.

Fix this by explicitly checking for rc = 0 as the only valid condition
to break out of the loop.

Fixes: 209c65b61d94 ("drivers/of/of_mdio.c:fix of_mdiobus_register()")
Reviewed-by: Andrew Lunn <[e-mail]>
Signed-off-by: Florian Fainelli <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/of/of_mdio.c

···
 				 child, addr);
 
 			if (of_mdiobus_child_is_phy(child)) {
+				/* -ENODEV is the return code that PHYLIB has
+				 * standardized on to indicate that bus
+				 * scanning should continue.
+				 */
 				rc = of_mdiobus_register_phy(mdio, child, addr);
-				if (rc && rc != -ENODEV)
+				if (!rc)
+					break;
+				if (rc != -ENODEV)
 					goto unregister;
-				break;
 			}
 		}
 	}