acpiphp: fix use of list_for_each macro

This patch fixes invalid usage of list_for_each()

list_for_each (node, &bridge_list) {
	bridge = (struct acpiphp_bridge *)node;
	...
}

This code works while the member of list node is located at the
head of struct acpiphp_bridge.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>