ARM: rmobile: salvator-x: Set default device tree

Set default device tree file in the salvator-x_defconfig
and use it in the environment.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/configs/salvator-x_defconfig b/configs/salvator-x_defconfig
index 9fb0b89..8cef607 100644
--- a/configs/salvator-x_defconfig
+++ b/configs/salvator-x_defconfig
@@ -3,6 +3,7 @@
 CONFIG_SYS_MALLOC_F_LEN=0x2000
 CONFIG_RCAR_GEN3=y
 CONFIG_TARGET_SALVATOR_X=y
+CONFIG_DEFAULT_FDT_FILE=r8a7795-salvator-x.dtb
 CONFIG_VERSION_VARIABLE=y
 CONFIG_CMD_BOOTZ=y
 CONFIG_CMD_FDT=y