can: peak_usb: report bus recovery as well

While the state changes are reported when the error counters increase
and decrease, there is no event when the bus recovers and the error
counters decrease again. So add those as well.

Change the state going downward to be ERROR_PASSIVE -> ERROR_WARNING ->
ERROR_ACTIVE instead of directly to ERROR_ACTIVE again.

Signed-off-by: Jeroen Hofstee <jhofstee@victronenergy.com>
Cc: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>