drm/omap: connector-analog-tv: Support only Composite type in legacy boot

In legacy mode (non DT mode) support only composite connector type. The
only user for this is rx51, using composite type.
Dropping the connector_type selection via pdata will allow cleanups in
omapdss (drm vs fbdev).

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>