OMAPDSS: acx565akm panel: handle gpios in panel driver

The acx565akm panel driver leaves gpio configurations to the platform_enable
and disable calls in the platform's board file. These should happen in the panel
driver itself.

Create a platform data struct for the panel, this contains the reset gpio number
used by the panel driver, this struct will be passed to the panel driver as
platform data. The driver will request and configure the reset gpio rather than
leaving it to platform callbacks in board files.

This will help in removing the need for the panel drivers to have platform
related callbacks.

Signed-off-by: Archit Taneja <archit@ti.com>