PCI: Use lockdep_assert_held(pci_bus_sem) to verify lock is held

PCI: Use lockdep_assert_held(pci_bus_sem) to verify lock is held

The function comment for pci_bus_max_d3cold_delay() declares pci_bus_sem
must be held while calling the function which can be automatically checked.
Add lockdep_assert_held(pci_bus_sem) to confirm pci_bus_sem is held.

Also mark the comment line with Context prefix.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20260116125742.1890-2-ilpo.jarvinen@linux.intel.com