drm/vmwgfx: Allow querying of the SVGA PCI id from the userspace

Mesa3D loaders require knowledge of the devices PCI id. SVGAv2 and v3
have different PCI id's, but the same driver is used to handle them both.
To allow Mesa3D svga driver to be loaded automatically for both SVGAv2
and SVGAv3 make the kernel return the PCI id of the currently running
device.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Reviewed-by: Maaz Mombasawala <mombasawalam@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220302152426.885214-6-zack@kde.org