drm/amdgpu: cleanup CS pass2 v6

Cleanup the coding style and function names to represent the data
they process for pass2 as well.

Go over the chunks only twice now instead of multiple times.

v2: fix job initialisation order and use correct scheduler instance
v3: try to move all functional changes into a separate patch.
v4: separate reordering, pass1 and pass2 change
v5: fix va_start calculation
v6: fix user fence check

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>