can: peak_pci: Fix the way channels are linked together

Change the way channels objects are linked together by peak_pci_probe()
avoiding any kernel oops when driver is removed. Side effect is that
the list is now browsed from last to first channel.

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