e1000e: cleanup: always return 0

These are a few instances of returning a value that can only be 0 so just
use a 'return 0' to make it more obvious.

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

@@ -1948,7 +1948,7 @@ static s32 e1000_set_d0_lplu_state_ich8lan(struct e1000_hw *hw, bool active)
 	u16 data;
 
 	if (phy->type == e1000_phy_ife)
-		return ret_val;
+		return 0;
 
 	phy_ctrl = er32(PHY_CTRL);