s390/appldata: reuse generic proc handler functions

Simplify appldata proc handlers by reusing generic proc handler functions.

Tested-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>