can: janz-ican3: avoid firmware lockup caused by infinite bus error quota

can: janz-ican3: avoid firmware lockup caused by infinite bus error quota

If the bus error quota is set to infinite and the host CPU cannot keep
up, the Janz VMOD-ICAN3 firmware will stop responding to control
messages until the controller is reset.

The firmware will automatically stop sending bus error messages when the
quota is reached, and will only resume sending bus error messages when
the quota is re-set to a positive value.

This limitation is worked around by setting the bus error quota to one
message, and then re-setting the quota to one message every time a bus
error message is received. By doing this, the firmware never stops
responding to control messages. The CAN bus can be reset without a
hard-reset of the controller card.

Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>