tc358767 driver sets the connector type always to eDP.

This patch sets the type to DP if there is no panel defined, which
implies that there's a DP connector on the board.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190103115954.12785-8-tomi.valkeinen@ti.com