Remove patch for QNN to use the legacy export flow.

[lucylq]

🐛 Describe the bug

QNN test failure on pin-update: #7273

Test: pull / test-llama-runner-qnn-linux (fp32, qnn_8a8w, qnn) / linux-job (pull_request)
Error logs:

Error:  [Qnn ExecuTorch]: graph_prepare.cc:204:ERROR:could not create op: q::ScatterNd.tcm

Error:  [Qnn ExecuTorch]: graph_prepare.cc:1377:ERROR:Op 0x12cb0000000b0 preparation failed with err:-1

Error:  [Qnn ExecuTorch]: QnnDsp <E> "aten_index_put_default_1" generated: could not create op

Error:  [Qnn ExecuTorch]: QnnDsp <E> RouterX86 graph prepare failed 12

Error:  [Qnn ExecuTorch]: QnnDsp <E> Failed to finalize graph (id: 1) with err 1002

Error:  [Qnn ExecuTorch]: Failed to finalize Qnn Graph with error: 1002
Error:  [Qnn ExecuTorch]: Fail to compile QNN graph

Potentially related to export changes in the pin-update from functional to non-functional IR. As a workaround, there is a patch to use the legacy export flow for QNN.

cc @tugsbayasgalan @cccclai

Versions

CI env.