drm/amdgpu: Unmap legacy queue when MES is enabled

This fixes a kernel oops when MES is not enabled.

Reported-by: Kenny Ho <Kenny.Ho@amd.com>
Suggested-by: Jack Xiao <Jack.Xiao@amd.com>
Reviewed-by: Alex Deucher <Alexander.Deucher@amd.com>
Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
Fixes: 18ee4ce6 ("drm/amdgpu: add mes unmap legacy queue routine")
Fixes: 3d879e81 ("drm/amdgpu: add init support for GFX11 (v2)")
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>