Currently only net-shell calls net_ppp_ping() command, so make
it return the amount of time that it took to receive Echo-Reply
so the net-shell can print the round trip time value.
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
By default PPP is started immediately when the network interface
goes up. This can be problematic especially when debugging the beast
so allow user to delay the startup.
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
