igb: Changed LEDs blink mechanism to include designs using cathode

This patch addresses the changes needed to make LEDs work properly with
negative logic. This implementation uses LED Invert bit to reverse the
logic issue that occurred when LEDs are driven by cathode. Keep LEDs
blinking for SerDes devices. Also made changes to magic number and the
for loop to reduce number of shifts.

Signed-off-by: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/igb/e1000_defines.h b/drivers/net/ethernet/intel/igb/e1000_defines.h
index 31a0f82..aa17649 100644
--- a/drivers/net/ethernet/intel/igb/e1000_defines.h
+++ b/drivers/net/ethernet/intel/igb/e1000_defines.h
@@ -270,8 +270,10 @@
 #define AUTONEG_ADVERTISE_SPEED_DEFAULT   E1000_ALL_SPEED_DUPLEX
 
 /* LED Control */
-#define E1000_LEDCTL_LED0_MODE_SHIFT      0
-#define E1000_LEDCTL_LED0_BLINK           0x00000080
+#define E1000_LEDCTL_LED0_MODE_SHIFT	0
+#define E1000_LEDCTL_LED0_BLINK		0x00000080
+#define E1000_LEDCTL_LED0_MODE_MASK	0x0000000F
+#define E1000_LEDCTL_LED0_IVRT		0x00000040
 
 #define E1000_LEDCTL_MODE_LED_ON        0xE
 #define E1000_LEDCTL_MODE_LED_OFF       0xF