ixgbe: add support for reporting 5G link speed

Since 5G link speed is supported by some devices, add reporting of 5G link
speed.
Signed-off-by: Paul Greenwalt <paul.greenwalt@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_main.c

@@ -7259,6 +7259,9 @@ static void ixgbe_watchdog_link_is_up(struct ixgbe_adapter *adapter)
 	case IXGBE_LINK_SPEED_10GB_FULL:
 		speed_str = "10 Gbps";
 		break;
+	case IXGBE_LINK_SPEED_5GB_FULL:
+		speed_str = "5 Gbps";
+		break;
 	case IXGBE_LINK_SPEED_2_5GB_FULL:
 		speed_str = "2.5 Gbps";
 		break;