i965/gen10: Implement Wa3DStateMode

i965/gen10: Implement Wa3DStateMode

This workaround doesn't fix any of the piglit hangs we've seen
on CNL. But it might be fixing something we haven't tested yet.

V2: Remove the bits enabling Float blend optimization. It is
    enabled through CACHE_MODE_SS register.
    Update the comment.
    Move gen10 if block on top of gen9 if block.

Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Rafael Antognolli <rafael.antognolli@intel.com>
Reviewed-by: Nanley Chery <nanley.g.chery@intel.com>