child-sa: Allocate a new reqid if dynamic traffic selectors are updated

child-sa: Allocate a new reqid if dynamic traffic selectors are updated

If update_sa() is called and dynamic traffic selectors are changed using
new addresses, this might cause issues if we continue to use a reqid that
doesn't match the updated traffic selectors.  For instance, if the initiator
then uses make-before-break reauth from the new IP.  It's also a particular
problem in the SELinux case where multiple CHILD_SAs with specific labels
all share the same (trap) policy with generic label.  However, SAs created
after the update would not match due to the new reqid.