can: m_can: m_can_handle_state_change(): fix state change

m_can_handle_state_change() is called with the new_state as an argument.

In the switch statements for CAN_STATE_ERROR_ACTIVE, the comment and the
following code indicate that a CAN_STATE_ERROR_WARNING is handled.

This patch fixes this problem by changing the case to CAN_STATE_ERROR_WARNING.

Signed-off-by: Wu Bo <wubo.oduw@gmail.com>
Link: http://lore.kernel.org/r/20200129022330.21248-2-wubo.oduw@gmail.com
Cc: Dan Murphy <dmurphy@ti.com>
Fixes: e0d1f481

 ("can: m_can: add Bosch M_CAN controller support")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>