OMAPDSS: panel-sharp-ls037v7dw01: update to use gpiod

Using gpiod will make it easier to add device tree support
for this panel in the following patches.

Note that all the GPIOs for this panel are optional, any
of the the GPIOs could be configured with external pulls
instead of GPIOs, so let's not error out if GPIOs are not
found to make the panel more generic.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>