ARM: dts: msm: Add panel TE source information for SM8150

Provide the TE source pin information about the DSI panel
which provides the vsync signal back to SM8150.

CRs-Fixed: 2254681
Change-Id: I43c1f16597b72bad139efe9ee24d1231c1a26fec
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>