sh: pass along struct pci_channel

These patches rework the pci code for the sh architecture.

Currently each board implements some kind of ioport to address mapping.
Some boards use generic_io_base others try passing addresses as io ports.
This is the first set of patches that try to unify the pci code as much
as possible to avoid duplicated code. This will in the end lead to fewer
lines board specific code and more generic code.

This patch makes sure a struct pci_channel pointer is passed along to
various pci functions such as pci_read_reg(), pci_write_reg(),
pci_fixup_pcic(), sh7751_pcic_init() and sh7780_pcic_init().

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>