sunxi: defconfig: add supported DT list for Pine64

When a board uses a FIT image to load U-Boot proper, it requires a list
of supported device trees to be supplied in CONFIG_OF_LIST, from which it
chooses the right one at runtime.
For boards with just one possible DT (like the OrangePi PC2) this
defaults to CONFIG_DEFAULT_DEVICE_TREE, but for the Pine64 with its two
possible models we provide all compatible DTs in this config symbol.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Jagan Teki <jagan@openedev.com>
Tested-by: Jagan Teki <jagan@openedev.com>

configs/pine64_plus_defconfig

@@ -3,6 +3,7 @@ CONFIG_ARCH_SUNXI=y
 CONFIG_MACH_SUN50I=y
 CONFIG_RESERVE_ALLWINNER_BOOT0_HEADER=y
 CONFIG_DEFAULT_DEVICE_TREE="sun50i-a64-pine64-plus"
+CONFIG_OF_LIST="sun50i-a64-pine64 sun50i-a64-pine64-plus"
 # CONFIG_SYS_MALLOC_CLEAR_ON_INIT is not set
 CONFIG_CONSOLE_MUX=y
 CONFIG_SPL=y