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

smatch reports the following warnings:
drivers/net/can/usb/peak_usb/pcan_usb_pro.c:514 pcan_usb_pro_drv_loaded() error: doing dma on the stack (buffer)
drivers/net/can/usb/peak_usb/pcan_usb_pro.c:878 pcan_usb_pro_init() error: doing dma on the stack (&fi)
drivers/net/can/usb/peak_usb/pcan_usb_pro.c:889 pcan_usb_pro_init() error: doing dma on the stack (&bi)

See "Documentation/DMA-API-HOWTO.txt" section "What memory is DMA'able?"

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