DISPC can drive data lines either on rising or falling pixel clock edge,
which can be configured by the user.

Sync lines can also be driven on rising or falling pixel clock edge, but
additionally the HW can be configured to drive the sync lines on
opposite clock edge from the data lines.

This opposite edge setting does not make any sense, as the same effect
can be achieved by just setting the sync lines to be driven on the other
edge compared to the data lines. It feels like some kind of backward
compatibility option, even if all DSS versions seem to have the same
implementation.

To simplify the code and configuration of the signals, and to make the
dispc timings more compatible with what is used on other platforms,
let's just remove the whole opposite-edge support.

The drivers that used OMAPDSS_DRIVE_SIG_OPPOSITE_EDGES setting are
changed so that they use the opposite setting from the data edge.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>