m68k: coldfire: select PCI_IOMAP for PCI

m68k: coldfire: select PCI_IOMAP for PCI

After I dropped CONFIG_GENERIC_IOMAP, some PCI drivers started failing
to link when CONFIG_MMU is disabled:

ERROR: modpost: "pci_iounmap" [drivers/video/fbdev/i740fb.ko] undefined!
ERROR: modpost: "pci_iounmap" [drivers/video/fbdev/vt8623fb.ko] undefined!
ERROR: modpost: "pci_iomap_wc" [drivers/video/fbdev/vt8623fb.ko] undefined!
ERROR: modpost: "pci_iomap" [drivers/video/fbdev/vt8623fb.ko] undefined!
ERROR: modpost: "pci_iounmap" [drivers/video/fbdev/s3fb.ko] undefined!
...

It turns out that there were two mistakes in my patch: on !MMU I forgot
to enable CONFIG_GENERIC_PCI_IOMAP, and for Coldfire with MMU enabled,
teh GENERIC_IOMAP was left in place but incorrectly configured.

Fixes: 9d48cc07d0d7 ("m68k/nommu: stop using GENERIC_IOMAP")
Reported-by: Greg Ungerer <gerg@linux-m68k.org>
Acked-by: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>