[mle] fix invalid router after ProcessRouteTlv (#5200)
[mle] fix invalid router after ProcessRouteTlv (#5200)

We always need to update existing router references after calling
ProcessRouteTlv.
lanyuwen/openthread,bukepo/openthread,chshu/openthread,lanyuwen/openthread,chshu/openthread,srickardti/openthread,jwhui/openthread,bukepo/openthread,chshu/openthread,openthread/openthread,openthread/openthread,srickardti/openthread,abtink/openthread,lanyuwen/openthread,srickardti/openthread,srickardti/openthread,openthread/openthread,lanyuwen/openthread,chshu/openthread,lanyuwen/openthread,abtink/openthread,jwhui/openthread,chshu/openthread,abtink/openthread,lanyuwen/openthread,bukepo/openthread,chshu/openthread,abtink/openthread,openthread/openthread,jwhui/openthread,jwhui/openthread,bukepo/openthread