drm/bridge: tc358767: add defines for DP1_SRCCTRL & PHY_2LANE

DP1_SRCCTRL register and PHY_2LANE field did not have matching defines.
Add these.

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/20190103115954.12785-3-tomi.valkeinen@ti.com