ssl_ciphersuites: remove MBEDTLS_KEY_EXCHANGE_SOME_XXDH_1_2_ENABLED

This symbol is unused in the code so it can be removed.

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/include/mbedtls/ssl_ciphersuites.h b/include/mbedtls/ssl_ciphersuites.h
index 6a80520..5d5b4b9 100644
--- a/include/mbedtls/ssl_ciphersuites.h
+++ b/include/mbedtls/ssl_ciphersuites.h
@@ -323,11 +323,6 @@
 #define MBEDTLS_KEY_EXCHANGE_SOME_ECDH_OR_ECDHE_ANY_ENABLED
 #endif
 
-/* TLS 1.2 XXDH key exchanges: ECDH or ECDHE */
-#if defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDH_OR_ECDHE_1_2_ENABLED)
-#define MBEDTLS_KEY_EXCHANGE_SOME_XXDH_1_2_ENABLED
-#endif
-
 /* The handshake params structure has a set of fields called xxdh_psa which are used:
  * - by TLS 1.2 to do ECDH or ECDHE;
  * - by TLS 1.3 to do ECDHE or FFDHE.