efi_loader: guard against double inclusion of efi_loader.h

Use a define to detect double inclusion of efi_loader.h.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/include/efi_loader.h b/include/efi_loader.h
index af64b11..e506eee 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -6,6 +6,9 @@
  *  SPDX-License-Identifier:     GPL-2.0+
  */
 
+#ifndef _EFI_LOADER_H
+#define _EFI_LOADER_H 1
+
 #include <common.h>
 #include <part_efi.h>
 #include <efi_api.h>
@@ -345,4 +348,6 @@
 				   const char *path) { }
 static inline void efi_net_set_dhcp_ack(void *pkt, int len) { }
 
-#endif
+#endif /* CONFIG_EFI_LOADER && !CONFIG_SPL_BUILD */
+
+#endif /* _EFI_LOADER_H */