not currently
possible) but it certainly doesn't make sense to build it as neither!
Add dependencies and add a choice group to ensure that exactly one of
FB_MB862XX_PCI_GDC and FB_MB862XX_LIME is selected.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Acked-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>