i965/fs: Use type-W for immediate in SampleID setup.

Not a functional difference, but register is loaded with a signed
immediate (V) and added to a signed type (D) producing a signed result
(D).

Also change the type of g0 to allow for compaction.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
2 files changed