can: peak_usb: add forgotten supported devices

Since the peak_usb driver also supports the CAN-USB interfaces
"PCAN-USB X6" and "PCAN-Chip USB" from PEAK-System GmbH, this patch adds
their names to the list of explicitly supported devices.

Fixes: ea8b65b5 ("can: usb: Add support of PCAN-Chip USB stamp module")
Fixes: f00b534d

 ("can: peak: Add support for PCAN-USB X6 USB interface")
Link: https://lore.kernel.org/r/20210309082128.23125-3-s.grosjean@peak-system.com
Signed-off-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>