sh-pfc: Terminate gpios array by -1

0 is a valid GPIO value, use -1 to terminate the gpios array in IRQ
lists.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>