plat/arm: enlarge the BL2 size on Arm platforms when TBB is enabled

For Trusted Board Boot, BL2 needs more space to support the ECDSA
and ECDSA+RSA algorithms.

Change-Id: Ie7eda9a1315ce836dbc6d18d6588f8d17891a92d
Signed-off-by: Qixiang Xu <qixiang.xu@arm.com>
diff --git a/include/drivers/auth/mbedtls/mbedtls_config.h b/include/drivers/auth/mbedtls/mbedtls_config.h
index ca2d9fa..96587ac 100644
--- a/include/drivers/auth/mbedtls/mbedtls_config.h
+++ b/include/drivers/auth/mbedtls/mbedtls_config.h
@@ -76,12 +76,13 @@
 #define MBEDTLS_MPI_WINDOW_SIZE              2
 #define MBEDTLS_MPI_MAX_SIZE               256
 
-/* System headers required to build mbed TLS with the current configuration */
-#include <stdlib.h>
-
 /* Memory buffer allocator options */
 #define MBEDTLS_MEMORY_ALIGN_MULTIPLE        8
 
+#ifndef __ASSEMBLY__
+/* System headers required to build mbed TLS with the current configuration */
+#include <stdlib.h>
 #include "mbedtls/check_config.h"
+#endif
 
 #endif /* __MBEDTLS_CONFIG_H__ */