pinctrl: pinconf: remove needless loop

This removes a needless loop which was caught in pinconf.c.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Laurent Meunier <laurent.meunier@st.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>