disp: msm: sde: set different wd timer according to te source

For dual panel, if they both used sim TE, the vsync sources
were set to the same watchdog timer. That's wrong, so need to
set different watchdog timer for different panels.

Change-Id: I8a5b4c6bb86b0b640d24fbfe6517e223d313fb68
Signed-off-by: Yuan Zhao <yzhao@codeaurora.org>