When the LEDs are driven by cathode, the bit logic is reversed.  Use the
LED Invert bit to invert the logic.  Cleanup use of a magic number and
change the for loop increment to reduce the number of shifts.
Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>