iris: Use modfiy disables for 3DSTATE_WM_DEPTH_STENCIL command

iris: Use modfiy disables for 3DSTATE_WM_DEPTH_STENCIL command

Add new IRIS_DIRTY_STENCIL_REF dirty flag which would help us to trigger
separate 3DSTATE_WM_DEPTH_STENCIL packet using modify disable fields.

Instead of merging two packets into one in order to build
3DSTATE_WM_DEPTH_STENCIL state, set_stencil_ref can use
IRIS_DIRTY_STENCIL_REF bit and bind_zsa_state can use
IRIS_DIRTY_WN_DEPTH_STENCIL, both could cause packet to happen with
available information using modify disable bits which allow us to
construct packet by ignoring set of fields.

v2: (Kenneth Graunke)
- Fix condition ordering.
- Club GEN cases.

Signed-off-by: Sagar Ghuge <sagar.ghuge@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3688>