drm/amdgpu/vce2: fix ip block reference

Need to use the correct IP block type.  VCE vs VCN.
Fixes mclk issues on Hawaii.

Suggested by selendym.

Fixes: 82ae6619 ("drm/amdgpu: update the handle ptr in wait_for_idle")
Closes: drm/amd#3997


Reviewed-by: Boyuan Zhang <Boyuan.Zhang@amd.com>
Cc: Sunil Khatri <sunil.khatri@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 02438acd)
Cc: stable@vger.kernel.org