[SECURITY] getpeersec: Fix build breakage

A recent changeset removes dummy_socket_getpeersec, replacing it with
two new functions, but still references the removed function in the
security_fixup_ops table, fix it by doing the replacement operation in
the fixup table too.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>