Remark update_res from __init to __devinit as it is called also
from __devinit functions.
This patch removes the following warning message:
WARNING: vmlinux.o(.devinit.text+0x774a): Section mismatch
in reference from the function pci_root_bus_res() to the
function .init.text:update_res()
The function __devinit pci_root_bus_res() references
a function __init update_res().
If update_res is only used by pci_root_bus_res then
annotate update_res with a matching annotation.