sunxi: dts: Add a CONFIG_DEFAULT_DEVICE_TREE setting to all sunxi boards

This is a preparation patch for switching all sunxi boards over to using
the driver model.

Note that rather then defining both CONFIG_DEFAULT_DEVICE_TREE (for u-boot)
and CONFIG_FDTFILE (for the kernel), this commit simply replaces all
CONFIG_FDTFILE defconfig settings with CONFIG_DEFAULT_DEVICE_TREE and
uses CONFIG_DEFAULT_DEVICE_TREE for setting the default fdtfile env value
in sunxi-common.h .

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
diff --git a/configs/Ainol_AW1_defconfig b/configs/Ainol_AW1_defconfig
index 5b3dd8b..ff41444 100644
--- a/configs/Ainol_AW1_defconfig
+++ b/configs/Ainol_AW1_defconfig
@@ -5,7 +5,7 @@
 # Also see: http://linux-sunxi.org/Ainol_AW1
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="AXP209_POWER"
-CONFIG_FDTFILE="sun7i-a20-ainol-aw1.dtb"
+CONFIG_DEFAULT_DEVICE_TREE="sun7i-a20-ainol-aw1"
 CONFIG_MMC0_CD_PIN="PH1"
 CONFIG_USB_MUSB_SUNXI=y
 CONFIG_USB0_VBUS_PIN="PB9"