m68k: add IO access definitions to support PCI on ColdFire platforms

Define the usual memory access functions (readb/writeb/...) and I/O space
functions (inb/outb/...) for PCI bus support on ColdFire CPU based platforms.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>