ARM: dts: at91: at91sam9n12: TC blocks are also simple-mfd and syscon devices

Add simple-mfd and syscon to the TC blocks to allow to register one of the
channels as clocksource properly at boot time and free up the remaining
channels for other use.

Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>