scripts: mkits.sh make it possible to specify fdt@#

Some bootloaders are really keen on just one special
fdt in a multi-image fit image. This is a problem, because
currently this is fixed to "fdt@1".

This patch introduces a new device variable:
DEVICE_FDT_NUM that allows to specify the right
fdt number.

If the value is absent "1" will be chosen.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

include/image-commands.mk

@@ -158,6 +158,7 @@ define Build/fit
 		-D $(DEVICE_NAME) -o $@.its -k $@ \
 		$(if $(word 2,$(1)),-d $(word 2,$(1))) -C $(word 1,$(1)) \
 		-a $(KERNEL_LOADADDR) -e $(if $(KERNEL_ENTRY),$(KERNEL_ENTRY),$(KERNEL_LOADADDR)) \
+		$(if $(DEVICE_FDT_NUM),-n $(DEVICE_FDT_NUM)) \
 		-c $(if $(DEVICE_DTS_CONFIG),$(DEVICE_DTS_CONFIG),"config@1") \
 		-A $(LINUX_KARCH) -v $(LINUX_VERSION)
 	PATH=$(LINUX_DIR)/scripts/dtc:$(PATH) mkimage -f $@.its $@.new

include/image.mk

@@ -432,6 +432,7 @@ define Device/Init
   DEVICE_DTS :=
   DEVICE_DTS_CONFIG :=
   DEVICE_DTS_DIR :=
+  DEVICE_FDT_NUM :=
   SOC :=
 
   BOARD_NAME :=
@@ -453,8 +454,9 @@ DEFAULT_DEVICE_VARS := \
   DEVICE_NAME KERNEL KERNEL_INITRAMFS KERNEL_INITRAMFS_IMAGE KERNEL_SIZE \
   CMDLINE UBOOTENV_IN_UBI KERNEL_IN_UBI BLOCKSIZE PAGESIZE SUBPAGESIZE \
   VID_HDR_OFFSET UBINIZE_OPTS UBINIZE_PARTS MKUBIFS_OPTS DEVICE_DTS \
-  DEVICE_DTS_CONFIG DEVICE_DTS_DIR SOC BOARD_NAME UIMAGE_NAME SUPPORTED_DEVICES \
-  IMAGE_METADATA KERNEL_ENTRY KERNEL_LOADADDR UBOOT_PATH IMAGE_SIZE \
+  DEVICE_DTS_CONFIG DEVICE_DTS_DIR DEVICE_FDT_NUM SOC BOARD_NAME \
+  UIMAGE_NAME SUPPORTED_DEVICES IMAGE_METADATA KERNEL_ENTRY KERNEL_LOADADDR \
+  UBOOT_PATH IMAGE_SIZE \
   DEVICE_COMPAT_VERSION DEVICE_COMPAT_MESSAGE \
   DEVICE_VENDOR DEVICE_MODEL DEVICE_VARIANT \
   DEVICE_ALT0_VENDOR DEVICE_ALT0_MODEL DEVICE_ALT0_VARIANT \