utvideo: Add ULH0 and ULH2 decoding to the native decoder.

Also prevents an error since the native decoder (if enabled) is
always used to probe Ut Video-encoded files, even if the user
forces libutvideo to be the decoder. Without this patch, the probe
would fail, and the video wouldn't get properly handed over,
resulting in failure to set codec parameters. When the native
decoder is disabled, libutvideo can probe and initialize decoding
without issues.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
