i965: Fix AA Line Distance Mode in 3DSTATE_SF on Ivybridge.

i965: Fix AA Line Distance Mode in 3DSTATE_SF on Ivybridge.

We were accidentally setting bit 14 in DWord 2 (which is Reserved/MBZ)
rather than bit 14 in DWord 3 (which is AA Line Distance Mode).

There's also no reason to ever set it to legacy mode; the bit is only
used when drawing antialiased lines anyway.  Set it unconditionally.

NOTE: This is a candidate for stable branches.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>