sh: pci: Move the se7751 fixups in to arch/sh/drivers/pci/.

The se7751 was still doing the PCI fixups in its own board directory,
so we move it over to arch/sh/drivers/pci/ with the rest of the board
fixups. It has bitrotted significantly over the years, so will still
likely need a bit of work to bring back up to date.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>