Use look-up table for base

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/cipher_wrap.h b/library/cipher_wrap.h
index 052cddb..06c8108 100644
--- a/library/cipher_wrap.h
+++ b/library/cipher_wrap.h
@@ -135,6 +135,8 @@
 
 extern int mbedtls_cipher_supported[];
 
+extern const mbedtls_cipher_base_t * mbedtls_cipher_base_lookup_table[];
+
 #ifdef __cplusplus
 }
 #endif