frontends/va: Return an error if non-interlaced buffer is not supported
Add a check to vaDeriveImage to see if a non-interlaced buffer was created successfully. Otherwise, return an error, since we won't be able to derive an image from the interlaced buffer.
Prevents a null pointer dereference from occuring on some nVidia cards, reported by Alexander Kapshuk.
Fixes: fcb55832 ("frontends/va: Derive image from interlaced buffers") Signed-off-by: Thong Thai thong.thai@amd.com