video: add DT node documentation for bridge chips

video: add DT node documentation for bridge chips

- Documentation is added for following chips
  - SN65DSI86: DSI to eDP bridge
  - SN65DSI85: DSI to LVDS bridge
  - MAX9291:   HDMI to GMSL bridge
  - DS90UB948: FPDLINK to LVDS bridge
  - DS90UH949: HDMI to FPDLINK bridge

Bug 200295087
JIRA EVLR-1240

Change-Id: Icae438030b2b047c76d24bb5bf716d375054147d
Signed-off-by: Deepak Bhosale <dbhosale@nvidia.com>
Reviewed-on: http://git-master/r/1471662
(cherry picked from commit d9cd3f00609d2a1858395b884e079a9938324f55)
Reviewed-on: http://git-master/r/1476439
GVS: Gerrit_Virtual_Submit
Reviewed-by: Vladislav Buzov <vbuzov@nvidia.com>