drm/i915/gvt: merge gvt.c into kvmgvt.c

The code in both files is deeply interconnected, so merge it and
keep a bunch of structures and functions static.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20220411141403.86980-30-hch@lst.de


Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>