can: flexcan: flexcan_remove(): disable wakeup completely

With below sequence, we can see wakeup default is enabled after re-load module,
if it was enabled before, so we need disable wakeup in flexcan_remove().

| # cat /sys/bus/platform/drivers/flexcan/5a8e0000.can/power/wakeup
| disabled
| # echo enabled > /sys/bus/platform/drivers/flexcan/5a8e0000.can/power/wakeup
| # cat /sys/bus/platform/drivers/flexcan/5a8e0000.can/power/wakeup
| enabled
| # rmmod flexcan
| # modprobe flexcan
| # cat /sys/bus/platform/drivers/flexcan/5a8e0000.can/power/wakeup
| enabled

Fixes: de3578c1 ("can: flexcan: add self wakeup support")
Fixes: 915f9666 ("can: flexcan: add support for DT property 'wakeup-source'")
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Link: https://lore.kernel.org/r/20201020184527.8190-1-qiangqing.zhang@nxp.com


[mkl: streamlined commit message]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>