efi_loader: git ignore helloworld_efi.S

Add *.S to .gitignore.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_loader/.gitignore b/lib/efi_loader/.gitignore
index 634a600..f2d7c14 100644
--- a/lib/efi_loader/.gitignore
+++ b/lib/efi_loader/.gitignore
@@ -1,2 +1,3 @@
 *.efi
 *.so
+*.S