drm/panel: jdi-lt070me05000: Use gpiod_set_value_cansleep

There is no reason why the control GPIOs for the panel can not
be connected to I2C or similar GPIO interfaces that may need to
sleep, therefore switch from gpiod_set_value to
gpiod_set_value_cansleep calls to configure them.
Without that you get complaints from gpiolib every time the state
is changed.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>