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>

configs/salvator-x_defconfig

@@ -3,6 +3,7 @@ CONFIG_ARCH_RMOBILE=y
 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

include/configs/rcar-gen3-common.h

@@ -100,7 +100,7 @@
 
 #define CONFIG_BOOTCOMMAND	\
 	"tftp 0x48080000 Image; " \
-	"tftp 0x48000000 Image-r8a7795-salvator-x.dtb; " \
+	"tftp 0x48000000 Image-"CONFIG_DEFAULT_FDT_FILE"; " \
 	"booti 0x48080000 - 0x48000000"
 
 #endif	/* __RCAR_GEN3_COMMON_H */