can: tcan4x5x: tcan4x5x_can_remove(): fix order of deregistration

Change the order in tcan4x5x_can_remove() to be the exact inverse of
tcan4x5x_can_probe(). First m_can_class_unregister(), then power down the
device.

Fixes: 5443c226

 ("can: tcan4x5x: Add tcan4x5x driver to the kernel")
Cc: Dan Murphy <dmurphy@ti.com>
Link: http://lore.kernel.org/r/20201019154233.1262589-10-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>