pico-imx6ul: Add DWARF baseboard support

This add the boot menu option for the DWARF baseboard as well as a
specific config file for users which wish to use it as a pre-defined
board.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
diff --git a/include/configs/pico-imx6ul.h b/include/configs/pico-imx6ul.h
index cd051bf..39c83a8 100644
--- a/include/configs/pico-imx6ul.h
+++ b/include/configs/pico-imx6ul.h
@@ -63,9 +63,11 @@
 		"rootfs part 0 1\0" \
 
 #define BOOTMENU_ENV \
-	"bootmenu_0=Boot using PICO-Hobbit baseboard=" \
+	"bootmenu_0=Boot using PICO-Dwarf baseboard=" \
+		"setenv fdtfile imx6ul-pico-dwarf.dtb\0" \
+	"bootmenu_1=Boot using PICO-Hobbit baseboard=" \
 		"setenv fdtfile imx6ul-pico-hobbit.dtb\0" \
-	"bootmenu_1=Boot using PICO-Pi baseboard=" \
+	"bootmenu_2=Boot using PICO-Pi baseboard=" \
 		"setenv fdtfile imx6ul-pico-pi.dtb\0" \
 
 #define CONFIG_SYS_MMC_IMG_LOAD_PART	1