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/UTOO_P66_defconfig b/configs/UTOO_P66_defconfig
index 7d97b3b..0815fd1 100644
--- a/configs/UTOO_P66_defconfig
+++ b/configs/UTOO_P66_defconfig
@@ -1,6 +1,6 @@
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="AXP209_POWER"
-CONFIG_FDTFILE="sun5i-a13-utoo-p66.dtb"
+CONFIG_DEFAULT_DEVICE_TREE="sun5i-a13-utoo-p66"
 CONFIG_USB_MUSB_SUNXI=y
 CONFIG_USB0_VBUS_PIN="PB04"
 CONFIG_USB0_VBUS_DET="PG01"