e1000e: Fix error handling in e1000_set_d0_lplu_state_82571

There is one e1e_wphy() call in e1000_set_d0_lplu_state_82571
that we have caught its return value but lack further handling.
Check and terminate the execution flow just like other e1e_wphy()
in this function.

Fixes: bc7f75fa ("[E1000E]: New pci-express e1000 driver (currently for ICH9 devices only)")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Acked-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/e1000e/82571.c

@@ -899,6 +899,8 @@ static s32 e1000_set_d0_lplu_state_82571(struct e1000_hw *hw, bool active)
 	} else {
 		data &= ~IGP02E1000_PM_D0_LPLU;
 		ret_val = e1e_wphy(hw, IGP02E1000_PHY_POWER_MGMT, data);
+		if (ret_val)
+			return ret_val;
 		/* LPLU and SmartSpeed are mutually exclusive.  LPLU is used
 		 * during Dx states where the power conservation is most
 		 * important.  During driver activity we should enable