can: peak_usb: pcan_usb_pro.h: remove double space in indention

This patch replaces the double space indention after the u8 with a
single space in pcan_usb_pro.h.

Link: https://lore.kernel.org/r/20210406111622.1874957-3-mkl@pengutronix.de
Acked-by: Stephane Grosjean <s.grosjean@peak-system.com>
Tested-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>