[POWERPC] ibmebus: Remove bus match/probe/remove functions

Remove old code that will be replaced by rewritten and shorter functions in
the next patch.  Keep struct ibmebus_dev and struct ibmebus_driver for now,
but replace ibmebus_{,un}register_driver() by dummy functions.  This way, the
kernel will still compile and run during the transition and git bisect will
be happy.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>