net: freescale: ucc_geth: Return early when TBI PHY can't be found

In ucc_geth's .mac_config(), we configure the TBI Serdes block represented by a
struct phy_device that we get from firmware.

While porting to phylink, a check was missed to make sure we don't try
to access the TBI PHY if we can't get it. Let's add it and return early
in case of error

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202601130843.rFGNXA5a-lkp@intel.com/
Fixes: 53036aa ("net: freescale: ucc_geth: phylink conversion")
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20260114080247.366252-1-maxime.chevallier@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: minimaxwell

drivers/net/ethernet/freescale/ucc_geth.c

@@ -1602,8 +1602,10 @@ static void ugeth_mac_config(struct phylink_config *config, unsigned int mode,
 			pr_warn("TBI mode requires that the device tree specify a tbi-handle\n");
 
 		tbiphy = of_phy_find_device(ug_info->tbi_node);
-		if (!tbiphy)
+		if (!tbiphy) {
 			pr_warn("Could not get TBI device\n");
+			return;
+		}
 
 		value = phy_read(tbiphy, ENET_TBI_MII_CR);
 		value &= ~0x1000;	/* Turn off autonegotiation */