Makefile: clean should delete *.efi

Files *.efi are generated files. So the clean target should delete them.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/Makefile b/Makefile
index 2995a19..1278cea 100644
--- a/Makefile
+++ b/Makefile
@@ -1625,7 +1625,8 @@
 		-o -name '*.symtypes' -o -name 'modules.order' \
 		-o -name modules.builtin -o -name '.tmp_*.o.*' \
 		-o -name 'dsdt.aml' -o -name 'dsdt.asl.tmp' -o -name 'dsdt.c' \
-		-o -name '*.gcno' \) -type f -print | xargs rm -f
+		-o -name '*.efi' -o -name '*.gcno' \) \
+		-type f -print | xargs rm -f
 
 # mrproper - Delete all generated files, including .config
 #