can: c_can: end pending transmission on network stop (ifdown)

commit 7ffd7b4e169d619e66928fe5d997723f2c6f1056 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>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>