can: peak_usb: fix mem leak in pcan_usb_pro_init()

This patch fixes a memory leak in pcan_usb_pro_init(). In patch

    f14e2243

 net: can: peak_usb: Do not do dma on the stack

the struct pcan_usb_pro_fwinfo *fi and struct pcan_usb_pro_blinfo *bi were
converted from stack to dynamic allocation va kmalloc(). However the
corresponding kfree() was not introduced.

This patch adds the missing kfree().

Cc: linux-stable <stable@vger.kernel.org> # v3.10
Reported-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>