pinctrl: sh-pfc: sh7372: Remove PFC support

Remove sh7372 PFC support as part of the sh7372 and Mackerel
legacy code removal.

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