MLK-16986-3: drm: mxsfb: fix connector handling

MLK-16986-3: drm: mxsfb: fix connector handling

Since the MXSFB initially was just a simple display pipe using a
drm_panel, the drm_connector was created "in-house", by mxsfb driver.
But, with latest changes, mxsfb also supports a bridge. In case of a
drm_bridge, the the connector is created and initialized by that bridge.
So, for a proper initialization during start-up, we need to take into
consideration that connector, instead of our "in-house" connector.
The connector created and initialized by mxsfb will be used only when
this driver will have a panel.

Signed-off-by: Robert Chiras <robert.chiras@nxp.com>
Reviewed-by: Laurentiu Palcu <laurentiu.palcu@nxp.com>