drm/amdgpu: fix typo for vcn2/jpeg2 idle check

fix typo for vcn2/jpeg2 idle check

Signed-off-by: James Zhu <James.Zhu@amd.com>
Reviewed-by: Leo Liu <leo.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>