Bitbang interface allows having a LED on one of the GPIO.
Let also linuxgpiod driver to specify and use the LED connection.
Change-Id: Id3d8772ee1808b92354fd073ba3947bacd8253ef
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5770
Tested-by: jenkins