[6.12.y] Please apply one upstream fix

[Artem Dinaburg]

Hi,

Please consider applying the following upstream commit to 6.12.y. It
applies cleanly to 6.12.112 and is already in 6.18.y and 7.2.y.

97110d42680e692020154f9aa89298c038196055
  PCI: endpoint: test: Synchronously cancel command handler work
  pci_epf_test_epc_deinit() and pci_epf_test_link_down() use the
  asynchronous cancel_delayed_work(), so the command handler can still
  run while DMA channels and BARs are released. The fix waits for it.

Build-tested on 6.12.y (CONFIG_PCI_EPF_TEST=m, CONFIG_WERROR=y); no
runtime testing.

Prepared with LLM assistance.

Thanks,
Artem Dinaburg