Fixup: Correct inclusion of legacy ECP headers in ssl.h
Previously, ecp.h was included only if MBEDTLS_ECDH_C was set,
which broke the build in configurations using ECDSA, but not ECDH.
An example of such a config is configs/config-thread.h, which
uses ECJPAKE exclusively.
Moreover, the inclusion of ecdh.h isn't needed, because the header
only uses constants defined in the ECP module.
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 9282fbc..79c6868 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -41,9 +41,8 @@
#include "dhm.h"
#endif
-#if defined(MBEDTLS_ECDH_C)
+#if defined(MBEDTLS_ECP_C)
#include "ecp.h"
-#include "ecdh.h"
#endif
#if defined(MBEDTLS_USE_TINYCRYPT)