ixgbe: Change register variable to unsigned

I noticed this variable used for register reads wasn't an unsigned
so this patch corrects that.  I don't believe this was causing any
issue as is but this is more consistent with the rest of the driver.
Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_common.c

@@ -2663,7 +2663,7 @@ s32 ixgbe_disable_rx_buff_generic(struct ixgbe_hw *hw)
  **/
 s32 ixgbe_enable_rx_buff_generic(struct ixgbe_hw *hw)
 {
-	int secrxreg;
+	u32 secrxreg;
 
 	secrxreg = IXGBE_READ_REG(hw, IXGBE_SECRXCTRL);
 	secrxreg &= ~IXGBE_SECRXCTRL_RX_DIS;