lenovo/t520: replace dumped GPIO values with gpio.h

GPIO pin wireing information from schematic

Change-Id: I2d8dca151b6fbc15e0184ea07596039570843cda
Signed-off-by: Nicolas Reinecke <nr@das-labor.org>
Reviewed-on: http://review.coreboot.org/6740
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>