split static functions in pci_host.h into pci_host.c and
pci_host_template.h.
Later a structures declared in pci_host.h, PCIHostState, will be used.
However pci_host.h doesn't allow to include itself easily. This patches
addresses it.

pci_host.h includes functions which are instantiated in .c by including
pci_host.h with typedefing pci_addr_t.
pci_addr_t is per pci host bridge and is typedef'ed to uint32_t for ioio
or target_phys_addr_t for mmio in .c file.
That prevents from including pci_host.h to use PCIHostState because of
requiring type, pci_addr_t.

Its purpose to include is to instantiate io function for mmio or ioio
depending on which pci host bridge requires ioio or mmio.
To avoid including code, we always instantiate both version.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>