OMAPDSS: Taal: remove rotate & mirror support

Taal panel driver has support to set rotation and mirroring. However,
these features cannot be used without causing tearing, and are never
used. The code is just extra bloat, so let's remove it.

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