[llvm] BPF: Change callx insn encoding (PR #81546)

[via llvm-commits]

yonghong-song wrote:

Windows test failed. The following are failed tests:
```
********************
Failed Tests (30):
  MLIR :: python/dialects/affine.py
  MLIR :: python/dialects/amdgpu.py
  MLIR :: python/dialects/arith_dialect.py
  MLIR :: python/dialects/arith_llvm.py
  MLIR :: python/dialects/cf.py
  MLIR :: python/dialects/func.py
  MLIR :: python/dialects/linalg/opdsl/arguments.py
  MLIR :: python/dialects/linalg/opdsl/assignments.py
  MLIR :: python/dialects/linalg/opdsl/doctests.py
  MLIR :: python/dialects/linalg/opdsl/emit_convolution.py
  MLIR :: python/dialects/linalg/opdsl/emit_matmul.py
  MLIR :: python/dialects/linalg/opdsl/emit_pooling.py
  MLIR :: python/dialects/linalg/opdsl/metadata.py
  MLIR :: python/dialects/linalg/opdsl/shape_maps_iteration.py
  MLIR :: python/dialects/linalg/opdsl/test_core_named_ops.py
  MLIR :: python/dialects/linalg/ops.py
  MLIR :: python/dialects/memref.py
  MLIR :: python/dialects/ml_program.py
  MLIR :: python/dialects/nvgpu.py
  MLIR :: python/dialects/python_test.py
  MLIR :: python/dialects/scf.py
  MLIR :: python/dialects/tensor.py
  MLIR :: python/dialects/transform_bufferization_ext.py
  MLIR :: python/dialects/transform_extras.py
  MLIR :: python/ir/blocks.py
  MLIR :: python/ir/builtin_types.py
  MLIR :: python/ir/diagnostic_handler.py
  MLIR :: python/ir/dialects.py
  MLIR :: python/ir/operation.py
  MLIR :: python/pass_manager.py
Testing Time: 63.76s
Total Discovered Tests: 2561
  Skipped          :    2 (0.08%)
  Unsupported      :  324 (12.65%)
  Passed           : 2202 (85.98%)
  Expectedly Failed:    1 (0.04%)
  Unresolved       :    2 (0.08%)
  Failed           :   30 (1.17%)
```
They are all MLIR python tests, and these failures are not really related to this patch.

https://github.com/llvm/llvm-project/pull/81546