e1000e: cleanup: do not assign a variable a value when not necessary

Static analysis with cppcheck has shown a few instances of a variable
being reassigned a value before the old one has been used.  None of these
ever require the old value to be used so remove the old values.

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/82571.c b/drivers/net/ethernet/intel/e1000e/82571.c
index d48143f..0f55d79 100644
--- a/drivers/net/ethernet/intel/e1000e/82571.c
+++ b/drivers/net/ethernet/intel/e1000e/82571.c
@@ -1397,7 +1397,7 @@
 {
 	u16 status_1kbt = 0;
 	u16 receive_errors = 0;
-	s32 ret_val = 0;
+	s32 ret_val;
 
 	/* Read PHY Receive Error counter first, if its is max - all F's then
 	 * read the Base1000T status register If both are max then PHY is hung.
@@ -1542,7 +1542,7 @@
 
 	ctrl = er32(CTRL);
 	status = er32(STATUS);
-	rxcw = er32(RXCW);
+	er32(RXCW);
 	/* SYNCH bit and IV bit are sticky */
 	udelay(10);
 	rxcw = er32(RXCW);
@@ -1812,7 +1812,7 @@
 static s32 e1000_read_mac_addr_82571(struct e1000_hw *hw)
 {
 	if (hw->mac.type == e1000_82571) {
-		s32 ret_val = 0;
+		s32 ret_val;
 
 		/* If there's an alternate MAC address place it in RAR0
 		 * so that it will override the Si installed default perm