OMAPDSS: Add some new fields to omap_video_timings

Some panel timing related fields are contained in omap_panel_config in the form
of flags. The fields are:

- Hsync logic level
- Vsync logic level
- Data driven on rising/falling edge of pixel clock
- Output enable/Data enable logic level
- HSYNC/VSYNC driven on rising/falling edge of pixel clock

Out of these parameters, Hsync and Vsync logic levels are a part of the timings
in the Xorg modeline configuration. So it makes sense to move the to
omap_video_timings. The rest aren't a part of modeline, but it still makes
sense to move these since they are related to panel timings.

These fields stored in omap_panel_config in dssdev are configured for LCD
panels, and the corresponding LCD managers in the DISPC_POL_FREQo registers.

Add the above fields in omap_video_timings. Represent their state via new enums.

Add these parameters to the omap_video_timings instances in the panel drivers.
Keep the corresponding IVS, IHS, IPC, IEO, RF and ONOFF flags in
omap_panel_config for now. The struct will be removed later.

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