bgpd: fix 'show bgp neighbors' output

bgpd: fix 'show bgp neighbors' output

The 'show bgp neighbors' output appends additional lines after GR mode
helpers.

> # show bgp neighbors
> [..]
>     End-of-RIB received: IPv4 VPN
>     Local GR Mode: Helper*
>
>     Remote GR Mode: Helper
>
>     R bit: True
>

Fix this by not appending the extra line feed.

> # show bgp neighbors
> [..]
>     End-of-RIB received: IPv4 VPN
>     Local GR Mode: Helper*
>     Remote GR Mode: Helper
>     R bit: True

Fixes: 0e4e879b4084 ("bgpd: fix silly format string SNAFU")
Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>