i965/fs: Revisit NIR atomic counter intrinsic translation.

i965/fs: Revisit NIR atomic counter intrinsic translation.

Rewrite the NIR atomic counter intrinsics translation code making use
of the recently introduced surface builder.  This will allow the
removal of some of the functionality duplicated between the visitor
and surface builder.

v2: Drop VEC4 suport.

Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>