pinctrl: exynos5440: fix invalid use of sizeof in exynos5440_pinctrl_probe()

sizeof() when applied to a pointer typed expression gives the
size of the pointer, not that of the pointed data.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>