drm/amdgpu: fix typo for vcn1 idle check

[ Upstream commit acfc62dc68770aa665cc606891f6df7d6d1e52c0 ]

fix typo for vcn1 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>
Signed-off-by: Sasha Levin <sashal@kernel.org>