drm/bridge: tc358767: cleanup spread & scrambler_dis

Minor cleanups:
- Use bool for boolean fields
- Use DP_MAX_DOWNSPREAD_0_5 instead of BIT(0)
- debug print down-spread and scrambler status

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190528082747.3631-5-tomi.valkeinen@ti.com