st/va: fix memory leak on error in vlVaCreateSurfaces2

Found by coverity: CID #1337953

Signed-off-by: Julien Isorce <j.isorce@samsung.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
1 file changed