PCI: Consolidate pci_bus/slot_lock/unlock/trylock()

PCI: Consolidate pci_bus/slot_lock/unlock/trylock()

pci_bus/slot_lock/unlock/trylock() largely duplicate the bus iteration loop
with variation only due to slot filter handling. The only differences in
the loops is where the struct bus is found (directly in the argument vs in
slot->bus) and whether slot filter is applied. Those differences are simple
to handle using function parameters.

Consolidate the bus iteration loop to one place by creating
__pci_bus_{lock,unlock,trylock}() and call them from the non-underscore
locking functions.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20260304122139.1479-1-ilpo.jarvinen@linux.intel.com