TLSSocketWrapper: do not force close() to block

Author: pennam

connectivity/netsocket/source/TLSSocketWrapper.cpp

@@ -757,7 +757,6 @@ nsapi_error_t TLSSocketWrapper::close()
 
     int ret = 0;
     if (_handshake_completed) {
-        _transport->set_blocking(true);
         ret = mbedtls_ssl_close_notify(&_ssl);
         if (ret) {
             print_mbedtls_error("mbedtls_ssl_close_notify", ret);