PCI: pciehp: Rename queue_interrupt_event() to pciehp_queue_interrupt_event()

Rename queue_interrupt_event() to pciehp_queue_interrupt_event() so we can
make it extern and call it from pcie_isr().

No functional change.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rajat Jain <rajatja@google.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>