net: openthread: make CONFIG_OPENTHREAD_NRF_SECURITY_PSA enable Mbed TLS

In some scenarios we would get an undefined reference to
mbedtls_debug_set_threshold() because Mbed TLS wouldn't be compiled in.

The proper fix for this would be to #ifdef out the use of this function
if it is the only undefined reference.

Signed-off-by: Tomi Fontanilles <tomi.fontanilles@nordicsemi.no>

Author: tomi-font

subsys/net/openthread/Kconfig

@@ -22,6 +22,7 @@ endchoice
 
 config OPENTHREAD_NRF_SECURITY_PSA
 	bool
+	select MBEDTLS
 	select MBEDTLS_ENABLE_HEAP if (!OPENTHREAD_COPROCESSOR_RCP && !BUILD_WITH_TFM && !PSA_SSF_CRYPTO_CLIENT)
 	select MBEDTLS_TLS_LIBRARY if (OPENTHREAD_JOINER || OPENTHREAD_COMMISSIONER || OPENTHREAD_COAPS || OPENTHREAD_BLE_TCAT || OPENTHREAD_SHELL)
 	select MBEDTLS_PEM_PARSE_C if (OPENTHREAD_COAPS || OPENTHREAD_BLE_TCAT)