drm: simple_kms_helper: make connector optional at init time

drm: simple_kms_helper: make connector optional at init time

drm_simple_display_pipe_init() pretends to attach a connector
to the display pipe.

In case a drm bridge has to be used, then it's the bridge that
takes care of connectors.

This patch makes the connector parameter optional for
drm_simple_display_pipe_init(), so that a drm bridge could
handle connector by itself later.

Signed-off-by: Andrea Merello <[email protected]>
Reviewed-by: Daniel Vetter <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Noralf Trønnes <[email protected]>
Cc: Daniel Vetter <[email protected]>
Signed-off-by: Archit Taneja <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]