can: usb: PEAK-System Technik PCAN-USB specific part

This patch adds the specific part which handles the PCAN-USB adapter from
PEAK-System Technik (http://www.peak-system.com). The PCAN-USB adapter is
a sja1000 based, mono-channel USB 1.1 adapter compliant with CAN
specifications 2.0A (11-bit ID) and 2.0B (29-bit ID).
Tested-by: NOliver Hartkopp <socketcan@hartkopp.net>
Acked-by: NWolfgang Grandegger <wg@grandegger.com>
Signed-off-by: NStephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/usb/peak_usb/Makefile

 obj-$(CONFIG_CAN_PEAK_USB) += peak_usb.o
-peak_usb-y = pcan_usb_core.o
+peak_usb-y = pcan_usb_core.o pcan_usb.o