i965/drm: Drop GEM_SW_FINISH stuff.

i965/drm: Drop GEM_SW_FINISH stuff.

This is only useful when doing an incoherent CPU mapping of the current
scanout buffer.  That's a terrible plan, so we never do it.  We always
use an uncached GTT map.

So, this is useless.  Drop the code.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>