ARM: at91/dts: add pinctrl support for SSC peripheral

Add pinctrl support for SSC on AT91 dtsi files.

Signed-off-by: Bo Shen <voice.shen@atmel.com>
[nicolas.ferre@atmel.com: split dtsi and driver changes]
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Reluctantly-acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>