efi_loader: correct parameter check in LocateHandle()

If LocateHandle() does not find an entry EFI_NOT_FOUND has to be returned
even if BufferSize is NULL.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index 3ed08e7..0c92cc1 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -1364,28 +1364,28 @@
 		return EFI_INVALID_PARAMETER;
 	}
 
-	/*
-	 * efi_locate_handle_buffer uses this function for
-	 * the calculation of the necessary buffer size.
-	 * So do not require a buffer for buffersize == 0.
-	 */
-	if (!buffer_size || (*buffer_size && !buffer))
-		return EFI_INVALID_PARAMETER;
-
 	/* Count how much space we need */
 	list_for_each_entry(efiobj, &efi_obj_list, link) {
 		if (!efi_search(search_type, protocol, search_key, efiobj))
 			size += sizeof(void *);
 	}
 
+	if (size == 0)
+		return EFI_NOT_FOUND;
+
+	if (!buffer_size)
+		return EFI_INVALID_PARAMETER;
+
 	if (*buffer_size < size) {
 		*buffer_size = size;
 		return EFI_BUFFER_TOO_SMALL;
 	}
 
 	*buffer_size = size;
-	if (size == 0)
-		return EFI_NOT_FOUND;
+
+	/* The buffer size is sufficient but there is not buffer */
+	if (!buffer)
+		return EFI_INVALID_PARAMETER;
 
 	/* Then fill the array */
 	list_for_each_entry(efiobj, &efi_obj_list, link) {