RSA-fix for UBLOX_EVK_ODIN_W2

UBLOX_EVK_ODIN_W2 needs the RSA with Mbed OS 5.9 onwards, there is
some internal dependency which failed the linking (due to Client
optimizing the RSA out).

Ref. Mbed OS PR #6963

Author: Janne Kiiskila

configs/wifi_odin_v4.json

@@ -17,7 +17,7 @@
         	"value": "BUTTON1"
         }
     },
-    "macros": ["MBEDTLS_USER_CONFIG_FILE=\"mbedtls_mbed_client_config.h\""],
+    "macros": ["MBEDTLS_USER_CONFIG_FILE=\"mbedtls_mbed_client_config.h\"", "MBED_CONF_RSA_REQUIRED"],
     "target_overrides": {
         "*": {
             "target.features_add": ["LWIP", "COMMON_PAL"],

mbedtls_mbed_client_config.h

@@ -77,9 +77,17 @@
 #define MBEDTLS_ECDSA_C
 #define MBEDTLS_X509_CRT_PARSE_C
 
-// Remove RSA, save 20KB at total
-#undef MBEDTLS_RSA_C
-#undef MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED
+// Remove RSA, save 20KB at total.
+// However, with Mbed OS 5.9 onwards - UBLOX_EVK_ODIN_W2 must have RSA!
+// A more abstract macro define added for that which you can trigger via
+// macros -part in the mbed_app.json.
+#if !defined(MBED_CONF_RSA_REQUIRED)
+    #undef MBEDTLS_RSA_C
+    #undef MBEDTLS_PK_RSA_ALT_SUPPORT
+    #undef MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED
+    #undef MBEDTLS_KEY_EXCHANGE_RSA_ENABLED
+    #undef MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED
+#endif // !MBED_CONF_RSA_REQUIRED
 
 // Remove error messages, save 10KB of ROM
 #undef MBEDTLS_ERROR_C