mbedtls: add psa_crypto_init() when Mbed TLS acts a PSA crypto client

Ensure psa_crypto_init() is called during initialization when
Mbed TLS acts as a PSA crypto client. This will setup the PSA
crypto server for further calls.

Signed-off-by: Valerio Setti <vsetti@baylibre.com>

modules/mbedtls/zephyr_init.c

@@ -94,6 +94,12 @@ static int _mbedtls_init(void)
 	mbedtls_debug_set_threshold(CONFIG_MBEDTLS_DEBUG_LEVEL);
 #endif
 
+#if defined(CONFIG_MBEDTLS_PSA_CRYPTO_CLIENT)
+	if (psa_crypto_init() != PSA_SUCCESS) {
+		return -EIO;
+	}
+#endif
+
 	return 0;
 }