UPSTREAM: drm/virtio: fix memory leak of vfpriv on error return path

The allocation for vfpriv is being leaked on an error return path,
fix this by kfree'ing it before returning.

Detected by CoverityScan, CID#1475380 ("Resource Leak")

Fixes: 6a37c49a94a9 ("drm/virtio: Handle context ID allocation errors")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20181107203122.6861-1-colin.king@canonical.com


Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit 040b595a91b21b61d6e0d388394b79c85f614e7c)
Signed-off-by: Greg Hartman <ghartman@google.com>
BUG: 139386237
Change-Id: I67f199a9fa2243a79927c908cbc4f47ac9b16f3d