disp: msm: dsi: enable multi mode support for video mode panel

Multi-panel can't be supported by video panel, but multi panel
operating mode can be supported for video mode panel, so enable
multi-mode support for video mode panel for panel operating mode
switch.

Change-Id: I9a62ba0c880d13c7201235b9cb65728fa13e3232
Signed-off-by: Lei Chen <chenlei@codeaurora.org>