radeonsi: fix radeon create encoder return

radeonsi: fix radeon create encoder return

Previous patch missed a "return" when trying to modify the create encoder
function, which made the whole logic fail. Therefore, add the return back.

Fixes: b38b208ff8886e799d6a2 "radeonsi:create uvd hevc enc entry"
Signed-off-by: Boyuan Zhang <boyuan.zhang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>