sunxi: Correct typo CONFIG_FTDFILE => CONFIG_FDTFILE

Patch is the result of:
  sed -i -e 's/FTDFILE/FDTFILE/g' board/sunxi/Kconfig configs/* include/configs/sunxi-common.h
  sed -i -e 's/ftdfile/fdtfile/g' board/sunxi/Kconfig

Reported-by: Vagrant Cascadian <vagrant@debian.org>
Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Acked-by: Hans de Goede <hdegoede@redhat.com>
[ ijc -- s/Spotted-by/Reported-by/ and resolve conflict vs "remove
         redundant "SPL" from CONFIG_SYS_EXTRA_OPTIONS" ]
diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
index c61c650..7bdf958 100644
--- a/board/sunxi/Kconfig
+++ b/board/sunxi/Kconfig
@@ -36,7 +36,7 @@
 	string
 	default "sunxi"
 
-config FTDFILE
-	string "Default ftdfile env setting for this board"
+config FDTFILE
+	string "Default fdtfile env setting for this board"
 
 endif