i965: Mark all EGLimages as non-coherent.

i965: Mark all EGLimages as non-coherent.

EGLimages are shared with external users, and we don't know what they're
going to do with them.  They might scan them out.  They might access
them in a way that doesn't work with our explicit clflushing.

It's safest to simply mark them non-coherent.

Chris Wilson caught this problem and wrote a similar (though less
aggressive) patch to solve it; the miptree code has since undergone
a lot of refactoring so I had to rewrite it.

Cc: "17.2" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>