r600g: precompute some of the hw state

r600g: precompute some of the hw state

Idea is to build hw state at pipe state creation and
reuse them while keeping a non PM4 packet interface
btw winsys & pipe driver. This commit also force rebuild
of pm4 packet on each call to radeon_state_pm4 which
in turn slow down everythings, this will be addressed.

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