can: error: add definitions for the different CAN error thresholds

Currently, drivers are using magic numbers to derive the CAN error
states from the error counter. Add three macro declarations to
remediate this.

For reference, the error-active, error-passive and bus-off are defined
in ISO 11898, section 12.1.4.2 "Error counting". Although ISO 11898
does not define error-warning state, this extra value is also commonly
used and is thus also added.

Link: https://lore.kernel.org/all/20220719143550.3681-13-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>