ARM: dts: enable IOMUX for Broadcom Cygnus

This enables the IOMUX support for Broadcom Cygnus SoC

Signed-off-by: Ray Jui <rjui@broadcom.com>
Tested-by: Dmitry Torokhov <dtor@chromium.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>