i965: Port gen6+ 3DSTATE_WM to genxml.

i965: Port gen6+ 3DSTATE_WM to genxml.

Emit 3DSTATE_WM on Gen6+ using brw_batch_emit helper, that uses pack
structs from genxml.

v2:
   - Use render_bo helper to setup brw_address (Kristian)
   - Remove TODO and use BRW_PSCDEPTH_OFF.
v3:
   - A couple of style fixes (Ken)
   - Enable RASTRULE_UPPER_RIGHT on gen6+ instead of gen8+ (Ken)

Signed-off-by: Rafael Antognolli <rafael.antognolli@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>