arm: omap: board-sdp3430: use sharp panel's gpio handling

The omap3430sdp board file currently requests gpios required by the sharp_ls dpi
panel, and provides platform_enable/disable callbacks to configure them.

These tasks have been moved to the sharp_ls panel driver itself and shouldn't
be done in the board files.

Remove the gpio requests and the platform callbacks from the board file.
Add the gpio information to panel_sharp_ls037v7dw01_data so that it's
passed to the panel driver.

Out of sharp panel's configurable pins, all apart from resb_gpio are managed by
a CPLD on the display and set to a default value. Only the configurable pin is
passed to platform data.

The backlight GPIO doesn't go directly to the sharp panel, it is used to set up
a voltage supply which goes to the LED+ pin of the panel, hence it isn't passed
to panel as platform data, and configured in the board file itself. The
backlight used to previously toggle through the platform_enable/disable
callbacks, but now it is always on. This needs to be revisited.

Signed-off-by: Archit Taneja <archit@ti.com>
Cc: Tony Lindgren <tony@atomide.com>