efi: Avoid using dm_scan_other()

This function is defined by bootstd so using it precludes using that
feature. Use the board_early_init_r() feature instead.

Nove the affected code into a new file, so that it is clear that
this relates to board init.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi/Makefile b/lib/efi/Makefile
index a790d2d..232fa68 100644
--- a/lib/efi/Makefile
+++ b/lib/efi/Makefile
@@ -2,7 +2,7 @@
 #
 # (C) Copyright 2015 Google, Inc
 
-obj-$(CONFIG_EFI_APP) += efi_app.o efi.o
+obj-$(CONFIG_EFI_APP) += efi_app.o efi.o efi_app_init.o
 obj-$(CONFIG_EFI_STUB) += efi_info.o
 
 CFLAGS_REMOVE_efi_stub.o := -mregparm=3 \