iucv: kernel option for z/VM IUCV and HiperSockets

When adding HiperSockets transport to AF_IUCV Sockets, af_iucv either
depends on IUCV or QETH_L3 (or both). This patch introduces the
necessary changes for kernel configuration.

Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>