net/iucv: fix kernel doc comments

Fix kernel doc comments where appropriate or remove incorrect kernel
doc indicators.
Also move kernel doc comments directly before functions.

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>