ip vrf: Add command name next to pid

ip vrf: Add command name next to pid

'ip vrf pids' is used to list processes bound to a vrf, but it only
shows the pid leaving a lot of work for the user. Add the command
name to the output. With this patch you get the more user friendly:

    $ ip vrf pids mgmt
     1121  ntpd
     1418  gdm-session-wor
     1488  gnome-session
     1491  dbus-launch
     1492  dbus-daemon
     1565  sshd
     ...

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>