[S390] hvc_iucv: Change IUCV term id and use one device as default

The patch renames the IUCV application ID from "ihvc" to "lnxhvc".
The device driver allocates one IUCV terminal device (lnxhvc0) as default.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>