drm/amdgpu: drop the GCR packet from the emit_ib frame for sdma5.0

It's not needed here and has been added to the proper place
in the previous patch.  This aligns with what we do for sdma 5.2.

Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>