debug: keep ECDH_C guard for debug printf accessing ecdh_context's items

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/debug.c b/library/debug.c
index 8c33f82..56bc3f6 100644
--- a/library/debug.c
+++ b/library/debug.c
@@ -397,7 +397,8 @@
 }
 #endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_X509_REMOVE_INFO */
 
-#if defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDH_OR_ECDHE_ANY_ENABLED)
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDH_OR_ECDHE_ANY_ENABLED) && \
+    defined(MBEDTLS_ECDH_C)
 static void mbedtls_debug_printf_ecdh_internal(const mbedtls_ssl_context *ssl,
                                                int level, const char *file,
                                                int line,
@@ -443,6 +444,7 @@
     }
 #endif
 }
-#endif /* MBEDTLS_KEY_EXCHANGE_SOME_ECDH_OR_ECDHE_ANY_ENABLED */
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_ECDH_OR_ECDHE_ANY_ENABLED &&
+          MBEDTLS_ECDH_C */
 
 #endif /* MBEDTLS_DEBUG_C */