tbbr-cot: conditional definition for the macro

Conditional definition for the macro MAX_NUMBER_IDS.

This will allow to update this definition by the platform
specific implementation.

Since, NXP SoC lx2160a based platforms requires additional
FIP DDR to be loaded before initializing the DDR.

It requires addition of defines for DDR image IDs.
A dedicated header plat_tbbr_img_def.h is added to the platform
folder - plat/nxp/common/include/default/

Inclusion of this header file will depend on the compile time
flag PLAT_TBBR_IMG_DEF.
Signed-off-by: Pankaj Gupta <pankaj.gupta@nxp.com>
Change-Id: I4faba74dce578e2a34acbc8915ff75d7b8368cee

include/common/tbbr/tbbr_img_def.h

 /*
- * Copyright (c) 2015-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -21,9 +21,17 @@
 #define SP_PKG7_ID			(MAX_IMAGE_IDS + 8)
 #define SP_PKG8_ID			(MAX_IMAGE_IDS + 9)
 #define MAX_SP_IDS			U(8)
-#define MAX_NUMBER_IDS			(MAX_IMAGE_IDS + MAX_SP_IDS + U(2))
+#define MAX_IMG_IDS_WITH_SPMDS		(MAX_IMAGE_IDS + MAX_SP_IDS + U(2))
 #else
-#define MAX_NUMBER_IDS			MAX_IMAGE_IDS
+#define MAX_IMG_IDS_WITH_SPMDS		MAX_IMAGE_IDS
+#endif
+
+#ifdef PLAT_TBBR_IMG_DEF
+#include <plat_tbbr_img_def.h>
+#endif
+
+#ifndef MAX_NUMBER_IDS
+#define MAX_NUMBER_IDS			MAX_IMG_IDS_WITH_SPMDS
 #endif
 
 #endif /* TBBR_IMG_DEF_H */