audit: disable ipsec auditing when CONFIG_AUDITSYSCALL=n

Disables auditing in ipsec when CONFIG_AUDITSYSCALL is
disabled in the kernel.

Also includes a bug fix for xfrm_state.c as a result of
original ipsec audit patch.

Signed-off-by: Joy Latten <latten@austin.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
Signed-off-by: David S. Miller <davem@davemloft.net>