OMAPFB: Map the newly added omap_video_timings fields with fb sync flags

Use the newly added fields in omap_video_timings(hsync, vsync and data_enable
logic levels and data, hsync and vsync latching related info) to
configure/retrieve corresponding sync flags in fb_var_screeninfo and
fb_videomode.

Out of the new fields, hsync_level and vsync_level can be mapped to the fb sync
flags FB_SYNC_HOR_HIGH_ACT and FB_SYNC_VERT_HIGH_ACT.

When converting fb mode to omap_video_timings, the fields which don't have an
equivalent parameter in fb are kept as the original values if the panel driver
has a get_timings op, else they are set to default values.

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