aco/isel: refactor emit_vop3a_instruction() to handle 2 operand instructions

Only AC:O has been affected.

Totals from 4 (0.00% of 136546) affected shaders (RAVEN):
CodeSize: 16428 -> 16420 (-0.05%)
Instrs: 3294 -> 3292 (-0.06%)
Cycles: 14208 -> 14200 (-0.06%)
VMEM: 936 -> 978 (+4.49%)
VClause: 80 -> 77 (-3.75%)
Copies: 211 -> 209 (-0.95%)
PreVGPRs: 127 -> 126 (-0.79%)

Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6635>
1 file changed