ACPI: work around duplicate name "VID" problem on T61

This can only fix the problem that more than one video bus device
have the same AML name "VID".
ie. the proc I/F for the second "VID" video bus device is located under
/proc/acpi/video/VID1/...

As this is really rare and the ACPI proc I/F is a legacy feature that
we are planning to remove.
We won't provide a generic solution for this problem.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>