efi_selftest: add tool to download dtb

For validating the fixed up device tree we need a tool to need to save it
to a file.

dtbdump.efi copies the configuration table with the device tree to a file
on the same partition from which dtbdump.efi was invoked. The file name can
be entered on the console.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_selftest/Makefile b/lib/efi_selftest/Makefile
index 06d66cf..aabb743 100644
--- a/lib/efi_selftest/Makefile
+++ b/lib/efi_selftest/Makefile
@@ -8,6 +8,8 @@
 asflags-y += -DHOST_ARCH="$(HOST_ARCH)"
 ccflags-y += -DHOST_ARCH="$(HOST_ARCH)"
 
+CFLAGS_dtbdump_exit.o := $(CFLAGS_EFI) -Os -ffreestanding
+CFLAGS_REMOVE_dtbdump.o := $(CFLAGS_NON_EFI)
 CFLAGS_efi_selftest_miniapp_exit.o := $(CFLAGS_EFI) -Os -ffreestanding
 CFLAGS_REMOVE_efi_selftest_miniapp_exit.o := $(CFLAGS_NON_EFI)
 CFLAGS_efi_selftest_miniapp_return.o := $(CFLAGS_EFI) -Os -ffreestanding
@@ -76,6 +78,9 @@
 efi_selftest_miniapp_exit.efi \
 efi_selftest_miniapp_return.efi
 
+always += \
+dtbdump.efi
+
 $(obj)/efi_miniapp_file_image_exception.h: $(obj)/efi_selftest_miniapp_exception.efi
 	$(obj)/../../tools/file2include $(obj)/efi_selftest_miniapp_exception.efi > \
 	$(obj)/efi_miniapp_file_image_exception.h