commit 7ffd7b4e upstream.

Put controller into init mode in network stop to end pending transmissions. The
issue is observed in cases when transmitted frame is not acked.
Signed-off-by: Viktor Babrian <babrian.viktor@renyi.mta.hu>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>