pinctrl: mvebu: fix iomem pointer for dove pinctrl

There has been a change in readl/writel to require registers
addresses marked as IOMEM(). This patch takes care of this and
also replaces ORing address offsets with adding them.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>