s390/net: add SMC config as one of the defaults of CCWGROUP

arch/s390/net/pnet.c uses ccwgroup function dev_is_ccwgroup()
in pnetid_by_dev_port().
For s390 the net/smc code makes use of function pnetid_by_dev_port().
Make sure ccwgroup is built into the kernel, if smc is to be built
into the kernel.

Signed-off-by: Guvenc Gulce <guvenc@linux.ibm.com>
Reviewed-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>