r600/sb: fix a bug emitting ar load from a constant.

Some tess shaders were doing MOVA_INT _, c0.x on cayman, and then
hitting an assert in sb_bc_finalize.cpp:translate_kcache.

This makes sure the toplevel kcache tracker gets updated,
and the clause gets fixed up.

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Cc: <mesa-stable@lists.freedesktop.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
(cherry picked from commit 68b976bd)