aco: Use s_pack_ll_b32_b16 for scalar zero extend.
Foz-DB Navi21:
Totals from 2403 (1.78% of 134913) affected shaders:
CodeSize: 25329156 -> 25311244 (-0.07%)
Foz-DB Navi21:
Totals from 2403 (1.78% of 134913) affected shaders:
CodeSize: 25329156 -> 25311244 (-0.07%)