[S390]: Rewrite of the IUCV base code, part 1

Remove the old IUCV code from drivers/s390/net
Remove approprirate IUCV entries from drivers/s390/net/Makefile,
drivers/s390/net/Kconfig and arch/s390/defconfig

Signed-off-by: Frank Pavlic <fpavlic@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>