can: move can_stats.bus_off++ from can_bus_off into can_change_state

In order to be able to move the stats increment from can_bus_off() into
can_change_state(), the increment had to be moved back into code that was using
can_bus_off() but not can_change_state().

As a side-effect, this patch fixes the following bugs:
 * Redundant call to can_bus_off() in c_can.
 * Bus-off counted twice in xilinx_can.

Signed-off-by: Andri Yngvason <andri.yngvason@marel.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
diff --git a/drivers/net/can/ti_hecc.c b/drivers/net/can/ti_hecc.c
index 9a07eaf..e95a9e1 100644
--- a/drivers/net/can/ti_hecc.c
+++ b/drivers/net/can/ti_hecc.c
@@ -715,6 +715,7 @@
 		hecc_clear_bit(priv, HECC_CANMC, HECC_CANMC_CCR);
 		/* Disable all interrupts in bus-off to avoid int hog */
 		hecc_write(priv, HECC_CANGIM, 0);
+		++priv->can.can_stats.bus_off;
 		can_bus_off(ndev);
 	}