SH: pci-sh7780: enable big-endian operation.

If in big-endian mode, switch the PCI bus, too.

Tested on both litte-endian and big-endian sh7785lcr.

Signed-off-by: Thomas Schwinge <thomas@codesourcery.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: linux-sh@vger.kernel.org
Signed-off-by: Paul Mundt <lethal@linux-sh.org>