efi_loader: move distro_efi_get_fdt_name()

Move distro_efi_get_fdt_name() to a separate C module
and rename it to efi_get_distro_fdt_name().

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
index 034e366..2af6f20 100644
--- a/lib/efi_loader/Makefile
+++ b/lib/efi_loader/Makefile
@@ -59,6 +59,7 @@
 obj-$(CONFIG_EFI_DEVICE_PATH_TO_TEXT) += efi_device_path_to_text.o
 obj-$(CONFIG_EFI_DEVICE_PATH_UTIL) += efi_device_path_utilities.o
 obj-y += efi_dt_fixup.o
+obj-y += efi_fdt.o
 obj-y += efi_file.o
 obj-$(CONFIG_EFI_LOADER_HII) += efi_hii.o
 obj-y += efi_image_loader.o