Makefile: Drop SPL_FIT_SOURCE support

The SPL_FIT_SOURCE is long superseded by SPL_FIT_GENERATOR which
is long superseded by binman, drop SPL_FIT_SOURCE support as there
are no more users.

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Peter Robinson <pbrobinson@gmail.com>
diff --git a/Makefile b/Makefile
index 3267fb1..6c637c6 100644
--- a/Makefile
+++ b/Makefile
@@ -1423,18 +1423,12 @@
 # or a generator script
 # NOTE: Please do not use this. We are migrating away from Makefile rules to use
 # binman instead.
-ifneq ($(CONFIG_SPL_FIT_SOURCE),"")
-U_BOOT_ITS := u-boot.its
-$(U_BOOT_ITS): $(subst ",,$(CONFIG_SPL_FIT_SOURCE))
-	$(call if_changed,copy)
-else
 ifneq ($(CONFIG_USE_SPL_FIT_GENERATOR),)
 U_BOOT_ITS := u-boot.its
 $(U_BOOT_ITS): $(U_BOOT_ITS_DEPS) FORCE
 	$(srctree)/$(CONFIG_SPL_FIT_GENERATOR) \
 	$(patsubst %,$(dt_dir)/%.dtb,$(subst ",,$(CONFIG_OF_LIST))) > $@
 endif
-endif
 
 ifdef CONFIG_SPL_LOAD_FIT
 MKIMAGEFLAGS_u-boot.img = -f auto -A $(ARCH) -T firmware -C none -O u-boot \
diff --git a/boot/Kconfig b/boot/Kconfig
index 925afe0..51e6cd6 100644
--- a/boot/Kconfig
+++ b/boot/Kconfig
@@ -282,14 +282,6 @@
 	  injected into the FIT creation (i.e. the blobs would have been pre-
 	  processed before being added to the FIT image).
 
-config SPL_FIT_SOURCE
-	string ".its source file for U-Boot FIT image"
-	depends on SPL_FIT
-	help
-	  Specifies a (platform specific) FIT source file to generate the
-	  U-Boot FIT image. This could specify further image to load and/or
-	  execute.
-
 config USE_SPL_FIT_GENERATOR
 	bool "Use a script to generate the .its script"
 	depends on SPL_FIT
diff --git a/doc/usage/fit/howto.rst b/doc/usage/fit/howto.rst
index b5097d4..280eff7 100644
--- a/doc/usage/fit/howto.rst
+++ b/doc/usage/fit/howto.rst
@@ -57,14 +57,9 @@
 multiple /configurations subnodes. The required images must be enumerated in
 the "loadables" property as a list of strings.
 
-If a platform specific image source file (.its) is shipped with the U-Boot
-source, it can be specified using the CONFIG_SPL_FIT_SOURCE Kconfig symbol.
-In this case it will be automatically used by U-Boot's Makefile to generate
-the image.
-If a static source file is not flexible enough, CONFIG_SPL_FIT_GENERATOR
-can point to a script which generates this image source file during
-the build process. It gets passed a list of device tree files (taken from the
-CONFIG_OF_LIST symbol).
+CONFIG_SPL_FIT_GENERATOR can point to a script which generates this image source
+file during the build process. It gets passed a list of device tree files (taken
+from the CONFIG_OF_LIST symbol).
 
 The SPL also records to a DT all additional images (called loadables) which are
 loaded. The information about loadables locations is passed via the DT node with