drm/omap: only ignore DIGIT SYNC LOST for TV output

We need to ignore DIGIT SYNC LOST error when enabling/disabling TV
output. The code does that, but it ignores the DIGI SYNC LOST when
enabling any output. Normally this does no harm, but it could make us
miss DIGIT SYNC LOST on some rare occasions.

Fix the code to only ignore DIGIT SYNC LOST when enabling/disabling TV.

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