ARM: dts: update syscons to use simple-mfd

The Integrators and the RealView use simple MFD devices with register bit
LEDs as subnodes, update these to use the "simple-mfd" compatible property
so that subdevices get spawned from the MFD nexi.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>