aco: take advantage of GFX10's constant bus limit and VOP3 literals

aco: take advantage of GFX10's constant bus limit and VOP3 literals

pipeline-db (Navi):
Totals from affected shaders:
SGPRS: 2397159 -> 2392494 (-0.19 %)
VGPRS: 1756036 -> 1753920 (-0.12 %)
Spilled SGPRs: 461 -> 470 (1.95 %)
Spilled VGPRs: 0 -> 0 (0.00 %)
Code Size: 110287304 -> 109946304 (-0.31 %) bytes
Max Waves: 318341 -> 318475 (0.04 %)
Instructions: 21019327 -> 20533618 (-2.31 %)

pipeline-db (Vega):
Totals from affected shaders:
SGPRS: 0 -> 0 (0.00 %)
VGPRS: 0 -> 0 (0.00 %)
Spilled SGPRs: 0 -> 0 (0.00 %)
Spilled VGPRs: 0 -> 0 (0.00 %)
Code Size: 0 -> 0 (0.00 %) bytes
Max Waves: 0 -> 0 (0.00 %)
Instructions: 0 -> 0 (0.00 %)

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/2883>