ARM: dts: add spi nodes for atmel SoC

Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
[wenyou.yang@atmel.com: add spi nodes for sam9260, sam9263, sam9g45 and sam9n12]
[wenyou.yang@atmel.com: remove spi property "cs-gpios" to the board dts files]
[wenyou.yang@atmel.com: submit the patch]
Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>