sh-pfc: r8a7791: add CAN pin groups

Add CAN0/1 data/clock pin groups to R8A7791 PFC driver.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>