OMAP: DSS2: Taal: Optimize enable_te, rotate, mirror when value unchanged

Skip any further processing of taal_enable_te(), taal_rotate(), and
taal_mirror() if value remains unchanged.

Signed-off-by: Jani Nikula <ext-jani.1.nikula@nokia.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>