intel/fs: Implement quad_swap_horizontal with a swizzle on gen7

This fixes dEQP-VK.subgroups.quad.compute.subgroupquadswaphorizontal_*
on all gen7 platforms.

Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Matt Turner <mattst88@gmail.com>
(cherry picked from commit 8fd2f2c2)