udoo_neo: Use 'fdtfile' variable name

'fdtfile' is the preferred name for the variable that contains the
device tree blob according to the README file.

It also makes it consistent with other i.MX boards that use config_distro,
so change it accordingly.
Signed-off-by: NFabio Estevam <fabio.estevam@nxp.com>

include/configs/udoo_neo.h

@@ -34,21 +34,21 @@
 #define CONFIG_EXTRA_ENV_SETTINGS \
 	"fdt_high=0xffffffff\0" \
 	"initrd_high=0xffffffff\0" \
-	"fdt_file=undefined\0" \
+	"fdtfile=undefined\0" \
 	"fdt_addr=0x83000000\0" \
 	"ip_dyn=yes\0" \
 	"mmcdev=0\0" \
 	"mmcrootfstype=ext4\0" \
 	"findfdt="\
 		"if test $board_name = BASIC; then " \
-			"setenv fdt_file imx6sx-udoo-neo-basic.dtb; fi; " \
+			"setenv fdtfile imx6sx-udoo-neo-basic.dtb; fi; " \
 		"if test $board_name = BASICKS; then " \
-			"setenv fdt_file imx6sx-udoo-neo-basic.dtb; fi; " \
+			"setenv fdtfile imx6sx-udoo-neo-basic.dtb; fi; " \
 		"if test $board_name = FULL; then " \
-			"setenv fdt_file imx6sx-udoo-neo-full.dtb; fi; " \
+			"setenv fdtfile imx6sx-udoo-neo-full.dtb; fi; " \
 		"if test $board_name = EXTENDED; then " \
-			"setenv fdt_file imx6sx-udoo-neo-extended.dtb; fi; " \
-		"if test $fdt_file = UNDEFINED; then " \
+			"setenv fdtfile imx6sx-udoo-neo-extended.dtb; fi; " \
+		"if test $fdtfile = UNDEFINED; then " \
 			"echo WARNING: Could not determine dtb to use; fi; \0" \
 	"kernel_addr_r=" __stringify(CONFIG_LOADADDR) "\0" \
 	"pxefile_addr_r=" __stringify(CONFIG_LOADADDR) "\0" \