can: m_can.c: fix setup of CCCR register: clear CCCR NISO bit before checking can.ctrlmode

Inside m_can_chip_config(), when setting up the new value of the CCCR,
the CCCR_NISO bit is not cleared like the others, CCCR_TEST, CCCR_MON,
CCCR_BRSE and CCCR_FDOE, before checking the can.ctrlmode bits for
CAN_CTRLMODE_FD_NON_ISO.

This way once the controller was configured for CAN_CTRLMODE_FD_NON_ISO,
this mode could never be cleared again.

This fix is only relevant for controllers with version 3.1.x or 3.2.x.
Older versions do not support NISO.

Signed-off-by: Roman Fietze <[e-mail]>
Cc: linux-stable <[e-mail]>
Signed-off-by: Marc Kleine-Budde <[e-mail]>

drivers/net/can/m_can/m_can.c

···
 
 	} else {
 	/* Version 3.1.x or 3.2.x */
-		cccr &= ~(CCCR_TEST | CCCR_MON | CCCR_BRSE | CCCR_FDOE);
+		cccr &= ~(CCCR_TEST | CCCR_MON | CCCR_BRSE | CCCR_FDOE |
+			  CCCR_NISO);
 
 		/* Only 3.2.x has NISO Bit implemented */
 		if (priv->can.ctrlmode & CAN_CTRLMODE_FD_NON_ISO)