arm: omap: board-omap3evm: use sharp panel's gpio handling

The omap3evm 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.

Note: The GPIOs OMAP3EVM_LCD_PANEL_ENVDD and OMAP3EVM_LCD_PANEL_BKLIGHT_GPIO
aren't directly connected to the sharp panel, hence they aren't passed to the
panel driver as platform data. These are set to a default value such that LCD
is enabled and backlight is on. These used to previously toggle through the
platform_enable/disable callbacks, but now these are always on. This needs to
be revisited.

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