aco: fix nir_op_pack_32_4x8 handling
What does this MR do and why?
aco: fix nir_op_pack_32_4x8 handling
Ever since commit 52ee4cf2292 ("nir/builder: Teach nir_pack_bits and
nir_unpack_bits about 32_4x8"), the operand of nir_op_pack_32_4x8 might
include swizzle and get_alu_src can return a vgpr. This fixes
ACO ERROR:
In file ../src/amd/compiler/aco_validate.cpp:98
Operand and Definition types do not match: s1: %44 = p_parallelcopy %158
test_basic: ../src/amd/compiler/aco_interface.cpp:85: void validate(aco::Program*):
Assertion `is_valid' failed.