[ET-VK][q8ta] Fix addmm arg indexing in QuantizedLinearMatch

[SS-JIA]

Stack from ghstack (oldest at bottom):

• [ET-VK][ez][qconv] Add auto-selection to prefer im2col for q8ta_conv2d #17568
• -> [ET-VK][q8ta] Fix addmm arg indexing in QuantizedLinearMatch #17567
• [ET-VK][q8ta] Add q8ta_linear_gemv op for batch-1 int8 linear #17566
• [ET-VK][q8ta] Add q8ta_linear operator for int8 quantized linear #17565
• [ET-VK][export] Update tensor representation sync logic to allow for flexibility in memory layouts #17564

QuantizedLinearMatch always used args[1] for the weight and args[0] for the
input, which is correct for mm(input, weight) and linear(input, weight, bias?)
but wrong for addmm(bias, input, weight) where the weight is at args[2] and the
input is at args[1].

This was exposed by a torchao change (D69887498) that added Linear+BatchNorm
fusion to prepare_pt2e(). The fusion adds a bias to Linear nodes that previously
had none, causing them to decompose to addmm instead of mm in the edge dialect.
The pattern matcher then read the input's per-tensor dequantize scale (a float
literal) as if it were the weight's per-channel scale (a Node), causing an
assertion failure.

The fix determines the correct arg indices based on whether the anchor node is
addmm. The bias handling at args[0] for addmm was already correct.

Authored-by: Claude

Differential Revision: D93768640

[pytorch-bot]

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❌ 3 New Failures, 59 Pending, 1 Unrelated Failure

As of commit 2a99758 with merge base 1056c34 ():

NEW FAILURES - The following jobs have failed:

• pull / test-mediatek-models-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 190191ad86a4b7cf18c6da6ede013a4a603a9d345f5a5af1405913c9d0c37c84 /exec failed with exit code 2
• pull / test-openvino-linux / linux-job (gh)
  RuntimeError: Command docker exec -t d760b9394ee4e824d05d07116ed12dcb0c379acc11127c56a5651bca77668a8d /exec failed with exit code 1
• pull / unittest-buck / linux / linux-job (gh)
  RuntimeError: Command docker exec -t 7ebd25228395074ab2963b20507d89ab1e371250050a2914aad8201dec22d613 /exec failed with exit code 3

BROKEN TRUNK - The following job failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / unittest-buck / macos / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 3

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