atheros: ar2315-pci: rework host controller initialization

atheros: ar2315-pci: rework host controller initialization

Explicitly configure PCI host controller, and do not expose it to PCI
subsystem. The PCI host controller acts as a usual PCI device connected
to the bus, but its configuration as a usual PCI device is senseless,
since the host controller provide access to _internal_ memory space for
_external_ device.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@42500 3c298f89-4303-0410-b956-a3cf2f4a3e73