OMAPDSS: Add a dispc_features struct for OMAP5

Add a dispc_features struct for OMAP5. Previously, OMAP5 used the same
struct as OMAP4. The new struct for OMAP5 contains the updated register
field offset and maximum limit for overlay manager width and height.

Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>