sh-pfc: r8a7740: Fix pin bias setup

When computing the pin configuration register offset the bias setup code
erroneously compares the pin number range with the loop index instead of
the pin number. Fix it.

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