pinctrl: cherryview: Introduce chv_readl() helper

There are plenty of places where we call
	readl(chv_padreg(pctrl, offset, ...));

Replace them with newly introduced chv_readl() helper
	chv_readl(pctrl, offset, ...);

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>