altoslib: Improve configuration performance over remote link

Avoid re-setting dongle radio parameters when they haven't changed
during device configuration setting. This avoids flipping back and
forth from remote to local mode three times during config save.

Wait for remote end to say 'Saved' before dropping radio link. This
ensures that the remote end actually gets the save command before the
link is terminated.

Signed-off-by: Keith Packard <keithp@keithp.com>