net/af_iucv: set correct sk_protocol for child sockets

[ Upstream commit c5dab094 ]

Child sockets erroneously inherit their parent's sk_type (ie. SOCK_*),
instead of the PF_IUCV protocol that the parent was created with in
iucv_sock_create().

We're currently not using sk->sk_protocol ourselves, so this shouldn't
have much impact (except eg. getting the output in skb_dump() right).

Fixes: eac3731b

 ("[S390]: Add AF_IUCV socket support")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Link: https://lore.kernel.org/r/20201120100657.34407-1-jwi@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>