ARM: at91: dt: add Calao USB-A9G20 low power version

the low power version have a mmc-spi

eanble mmc-spi and RV3029C2 RTC in at91_dt_defconfig

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

diff --cc arch/arm/boot/dts/Makefile
Simple merge

diff --cc arch/arm/boot/dts/usb_a9g20.dts
Simple merge

diff --cc arch/arm/boot/dts/usb_a9g20_common.dtsi
Simple merge

diff --cc arch/arm/boot/dts/usb_a9g20_lpw.dts
Simple merge

diff --cc arch/arm/configs/at91_dt_defconfig
Simple merge