can: proc: give variable holding the CAN per device receive lists a sensible name

This patch gives the variables holding the CAN per device receive filter lists
a better name by renaming them from "d" to "dev_rcv_lists".

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>