Current ACPIPHP driver scans only slots under the top level PCI-to-PCI
bridge. So hotplug PCI slots under the nested PCI-to-PCI bridge would
not be detected. For example, if the system has the ACPI namespace
like below, hotplug slots woule not be detected.

Device (PCI0) {						/* Root bridge */
	Name (_HID, "PNP0A03")
	Device (P2PA) {					/* PCI-to-PCI bridge */
		Name (_ADR, ...)
		Device (P2PB) {				/* PCI-to-PCI bridge */
			Name (_ADR, ...)
			Device (S0F0) {			/* hotplug slot */
				Name (_ADR, ...)
				Name (_SUN, ...)
				Method (_EJ0, ...) { ... }
			}
			...
			Device (S0F7) {			/* hotplug slot */
				Name (_ADR, ...)
				Name (_SUN, ...)
				Method (_EJ0, ...) { ... }
			}
			Device (S1F0) {			/* hotplug slot */
				Name (_ADR, ...)
				Name (_SUN, ...)
				Method (_EJ0, ...) { ... }
			}
			...
		}
	}
}

This patch fixes this issue.
Signed-off-by: NKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>