ARM: dts: at91: sam9x60ek: Add sdmmc1 node

sdmmc1 is not populated by default on sam9x60ek, but there are cases
where it is populated with wilc3000. Add the node, but keep it disabled.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20200403061222.1277147-4-tudor.ambarus@microchip.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>