kbuild: Provide a version of merge_into_defconfig without override warnings

While warning on overridden Kconfig options is a good default for merging
config fragements sometimes that is our explicit intent and the warnings
are unhelpful, add a new merge_into_defconfig_override which does the merge
but with warnings suppressed.

Since merge_into_defconfig accepts any number of fragments it is difficult
to allow it to accept the flag.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230203-arm64-defconfigs-v1-2-cd0694a05f13@kernel.orgSigned-off-by: Arnd Bergmann <arnd@arndb.de>

scripts/Makefile.defconf

@@ -13,3 +13,17 @@ define merge_into_defconfig
 		$(foreach config,$(2),$(srctree)/arch/$(ARCH)/configs/$(config).config)
 	+$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
 endef
+
+
+# Creates 'merged defconfigs without warning about overrides'
+# ---------------------------------------------------------------------------
+# Usage:
+#   $(call merge_into_defconfig_override,base_config,config_fragment1 config_fragment2 ...)
+#
+# Input config fragments without '.config' suffix
+define merge_into_defconfig_override
+	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh \
+		-Q -m -O $(objtree) $(srctree)/arch/$(ARCH)/configs/$(1) \
+		$(foreach config,$(2),$(srctree)/arch/$(ARCH)/configs/$(config).config)
+	+$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
+endef