OMAPDSS: generic dpi panel: remove uses of platform_enable/disable ops
The generic dpi panel driver now sets the gpios required to configure the panel.
This was previously done in platform_enable/disable callbacks in board files.
All the board files using generic dpi panel now correctly pass the gpio related
information as platform data, which is needed by the panel driver to configure
the panel. Hence, the platform_enable/disable ops can be safely removed now.