gstreamer1.0-plugins-bad: add support for vdpau

libvdpau support was added to meta-oe by commit bf1de4db2 ("libvdpau:
Add recipe") in 2016. Therefore add a packageconfig for the
corresponding gstreamer plugin.

Based on a patch by Richard Leitner <richard.leitner@skidata.com>

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>