pinctrl: baytrail: Fix debugfs offset output

Apparently each GPIO pad's register are 16 bytes, so multiply the pad_map
by that. The same is done in byt_gpio_reg the only other place where
pad_map is used.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>