r600g: order atom emission v3

r600g: order atom emission v3

To avoid GPU lockup registers must be emited in a specific order
(no kidding ...). This patch rework atom emission so order in which
atom are emited in respect to each other is always the same. We
don't have any informations on what is the correct order so order
will need to be infered from fglrx command stream.

v2: add comment warning that atom order should not be taken lightly
v3: rebase on top of alphatest atom fix

Signed-off-by: Jerome Glisse <jglisse@redhat.com>