PCI: aerdrv: make aer_{en,dis}able_rootport static

These functions are only called from init/remove path of aerdrv,
so move them from aerdrv_core.c to aerdrv.c, to make them static.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Reviewed-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>