net/netlabel/netlabel_kapi.c: add missing cleanup code

Call cipso_v4_doi_putdef in the case of the failure of the allocation of
entry.  Reverse the order of the error handling code at the end of the
function and insert more labels in order to reduce the number of
unnecessary calls to kfree.

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>