drm/radeon: clean up CS functions in r100.c

Consolidate the CS functions to one section of the file.
Previously they were spread all around.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>