net: fec: Fix possible NPD in fec_enet_phy_reset_after_clk_enable()

The function of_phy_find_device may return NULL, so we need to take
care before dereferencing phy_dev.

Fixes: 64a632d ("net: fec: Fix phy_device lookup for phy_reset_after_clk_enable()")
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Cc: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Cc: Richard Leitner <richard.leitner@skidata.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Wei Fang <wei.fang@nxp.com>
Link: https://patch.msgid.link/20250904091334.53965-1-wahrenst@gmx.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: lategoodbye

drivers/net/ethernet/freescale/fec_main.c

@@ -2363,7 +2363,8 @@ static void fec_enet_phy_reset_after_clk_enable(struct net_device *ndev)
 		 */
 		phy_dev = of_phy_find_device(fep->phy_node);
 		phy_reset_after_clk_enable(phy_dev);
-		put_device(&phy_dev->mdio.dev);
+		if (phy_dev)
+			put_device(&phy_dev->mdio.dev);
 	}
 }