can: flexcan: disable clocks during stop mode

Disable clocks while CAN core is in stop mode.

Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Tested-by: Sean Nyekjaer <sean@geanix.com>
Link: https://lore.kernel.org/r/20191210085721.9853-2-qiangqing.zhang@nxp.com


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>