pinctrl: sh-pfc: r8a7790: Fix vsync value in the vin3_sync_mux array

This fixes a typo in the vin3_sync_mux array (s/VI2/VI3/).

Signed-off-by: Valentine Barshak <valentine.barshak@cogentembedded.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>