tls: fix a comment a rename a variable/symbol

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index c08f5e1..b5e6ed2 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -757,14 +757,14 @@
 #endif /* !MBEDTLS_USE_PSA_CRYPTO &&
           MBEDTLS_KEY_EXCHANGE_SOME_ECDH_OR_ECDHE_1_2_ENABLED */
 
-#if defined(MBEDTLS_KEY_EXCHANGE_SOME_XXDH_ANY_PSA_ENABLED)
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_XXDH_PSA_ANY_ENABLED)
     psa_key_type_t xxdh_psa_type;
-    size_t xxdh_bits;
+    size_t xxdh_psa_bits;
     mbedtls_svc_key_id_t xxdh_psa_privkey;
     uint8_t xxdh_psa_privkey_is_external;
     unsigned char xxdh_psa_peerkey[PSA_EXPORT_PUBLIC_KEY_MAX_SIZE];
     size_t xxdh_psa_peerkey_len;
-#endif /* MBEDTLS_KEY_EXCHANGE_SOME_XXDH_ANY_PSA_ENABLED */
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_XXDH_PSA_ANY_ENABLED */
 
 #if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
 #if defined(MBEDTLS_USE_PSA_CRYPTO)