drm/amdgpu: fix when the cleaner shader is emitted

Emitting the cleaner shader must come after the check if a VM switch is
necessary or not.

Otherwise we will emit the cleaner shader every time and not just when it is
necessary because we switched between applications.

This can otherwise crash on gang submit and probably decreases performance
quite a bit.

v2: squash in fix from Srini (Alex)

Signed-off-by: Christian König <christian.koenig@amd.com>
Fixes: ee7a846e ("drm/amdgpu: Emit cleaner shader at end of IB submission")
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org