s390/netiucv: remove incorrect kernel doc indicators

Many comments above functions start with a kernel doc indicator, but
the comments are not using kernel doc style. Get rid of the warnings
by simply removing the indicator.

E.g.:

drivers/s390/net/netiucv.c:1852: warning:
 This comment starts with '/**', but isn't a kernel-doc comment.

Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>