tipc: bail out if algname is abnormally long

tipc: bail out if algname is abnormally long

tipc segfaults when called with an abnormally long algname:

$ tipc node set key 0x1234 algname supercalifragilistichespiralidososupercalifragilistichespiralidoso
*** buffer overflow detected ***: terminated

Fix this returning an error if provided algname is longer than
TIPC_AEAD_ALG_NAME.

Fixes: 24bee3bf9752 ("tipc: add new commands to set TIPC AEAD key")
Signed-off-by: Andrea Claudi <aclaudi@redhat.com>
Signed-off-by: David Ahern <dsahern@kernel.org>