revert "net: kcm: fix memory leak in kcm_sendmsg"

In commit c47cc304 ("net: kcm: fix memory leak in kcm_sendmsg")
I misunderstood the root case of the memory leak and came up with
completely broken fix.

So, simply revert this commit to avoid GPF reported by
syzbot.

Im so sorry for this situation.

Fixes: c47cc304

 ("net: kcm: fix memory leak in kcm_sendmsg")
Reported-by:  <syzbot+65badd5e74ec62cb67dc@syzkaller.appspotmail.com>
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>