e1000e: add missing bailout on error

...discovered during code inspection.
Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000e/ich8lan.c

@@ -2077,6 +2077,8 @@ static s32 e1000_lv_phy_workarounds_ich8lan(struct e1000_hw *hw)
 
 	/* Set MDIO slow mode before any other MDIO access */
 	ret_val = e1000_set_mdio_slow_mode_hv(hw);
+	if (ret_val)
+		return ret_val;
 
 	ret_val = hw->phy.ops.acquire(hw);
 	if (ret_val)