drm/i915: try another possible DDC bus for the SDVO device with multiple outputs

drm/i915: try another possible DDC bus for the SDVO device with multiple outputs

There exist multiple DDC buses for the SDVO cards with multiple outputs.
When we can't get the EDID by using the select DDC bus, we can try the other
possible DDC bus to see whether the EDID can be obtained.

https://bugs.freedesktop.org/show_bug.cgi?id=23842

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Tested-by: Sebastien Caty <sebastien.caty@mrnf.gouv.qc.ca>
Signed-off-by: Eric Anholt <eric@anholt.net>