vrrp: Add missing IP address comparison while receiving same prio advert in MASTER

Pevious code updated link and sent advert in MASTER mode if received advert was
lower prio than local instance prio. Extended the code to handle the same case
where incoming advert is the same prio but ip_src is lower than local instance
ip_src. This patch just speed up the election by automatically update remote
cache (v4 or v6).