drm/i915/gvt: Purge dev_priv->gt

Use the right intel_gt stored as a backpointer in intel_vgpu.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20210129004933.29755-2-chris@chris-wilson.co.uk


Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>