arm: omap: board-rx-51: use acx565akm panel's gpio handling

The rx-51 board file currently requests gpios required by the acx565akm panel,
and provides platform_enable/disable callbacks to configure them.

These tasks have been moved to the acx565akm panel driver itself and shouldn't
be done in the board files.

Remove the gpio requests and the platform callbacks from the board file. Pass
the panel_acx565akm_data instance 'lcd_data' to omap_dss_device instead of
passing the gpio number in omap_dss_device's reset_gpio.

Add the gpio information to panel_acx565akm_data so that it's passed to the
panel driver.

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