intel/compiler: make uses_pos_offset a tri-state

This value depends on the per-sample value which can be unknown at compile time with graphics pipeline libraries. So we need to have this dynamic has well and pick the right value when generating the 3DSTATE_PS/3DSTATE_WM packet.

Signed-off-by: Lionel Landwerlin lionel.g.landwerlin@intel.com Fixes: d8dfd153 ("intel/fs: Make per-sample and coarse dispatch tri-state")