efi_loader: use u16* for UTF16 strings

We should be consistent in the types that we use to store Unicode strings.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/include/efi_api.h b/include/efi_api.h
index e58dd05..aef77b6 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -965,7 +965,7 @@
 	struct efi_time last_access_time;
 	struct efi_time modification_time;
 	u64 attribute;
-	s16 file_name[0];
+	u16 file_name[0];
 };
 
 struct efi_file_system_info {