e1000e: do not ignore variables which get set a value

Static analysis with cppcheck has shown a few instances of a variable which
is assigned a value that is never used.  A number of these are the return
status of various driver function calls which should be passed back to the
caller of the current function.

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>
diff --git a/drivers/net/ethernet/intel/e1000e/phy.c b/drivers/net/ethernet/intel/e1000e/phy.c
index 3b97121..b4aaf69 100644
--- a/drivers/net/ethernet/intel/e1000e/phy.c
+++ b/drivers/net/ethernet/intel/e1000e/phy.c
@@ -3332,7 +3332,7 @@
 	         I82577_DSTATUS_CABLE_LENGTH_SHIFT;
 
 	if (length == E1000_CABLE_LENGTH_UNDEFINED)
-		ret_val = -E1000_ERR_PHY;
+		return -E1000_ERR_PHY;
 
 	phy->cable_length = length;