iris: Set XY Clipping correctly.

iris: Set XY Clipping correctly.

I was setting it based off a pipe_rasterizer_state field that appears
to be entirely dead outside of the draw module respecting it.

I should be setting it when the primitive type reaching the SF is
neither points nor lines.  This is, unfortunately, rather dirty,
as we have to look at the rasterizer state, the geometry shader state,
the tessellation evaluation shader state, and the primitive type...