JPEG Encoder: return supported pixel formats for vaQuerySurfaceAttributes
JPEG Encoder: return supported pixel formats for vaQuerySurfaceAttributes

Since commit d540e43 landed, we can query with VAEntrypointEncPicture
entrypoint for jpeg encoder. But it doesn't still return some formats,
which jpeg encoder is capable of handling.

Fixes #60

Signed-off-by: Hyunjun Ko <d9d1e41a6793af0da65104c04833718c857459dd@igalia.com>

01org/iotg-lin-gfx-va-driver,01org/iotg-lin-gfx-va-driver,01org/iotg-lin-gfx-va-driver,01org/iotg-lin-gfx-va-driver,01org/iotg-lin-gfx-va-driver