Consolidate duplicate code blocks both updating peer groups
Consolidate duplicate code blocks both updating peer groups

There were only two differences: 1) the first block updates
`updatePolicy` and 2) the log statements are a little bit different
(`pg.State` vs `pg.Config` and `%v` vs `%s`).

To be consistent with the other blocks above it, changed to use
`pg.Config` rather than `pg.State`.

fujita/gobgp,tamihiro/gobgp,a16/gobgp,a16/gobgp,a16/gobgp,osrg/gobgp,a16/gobgp,tamihiro/gobgp,j-kato/gobgp,tamihiro/gobgp,fujita/gobgp,j-kato/gobgp,fujita/gobgp,osrg/gobgp,a16/gobgp,a16/gobgp,fujita/gobgp,osrg/gobgp,a16/gobgp,osrg/gobgp,tamihiro/gobgp,j-kato/gobgp