drm/amdgpu/gfx7: fix CSIB handling

[ Upstream commit be7652c23d833d1ab2c67b16e173b1a4e69d1ae6 ]

We shouldn't return after the last section.
We need to update the rest of the CSIB.

Reviewed-by: Rodrigo Siqueira <siqueira@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>