samples: syslog_net: correctly late-initialize log backend

log_backend_activate() does not assign the backend id (backend->ctx->id),
which is required for runtime filtering.

Signed-off-by: Armin Brauns <armin.brauns@embedded-solutions.at>

samples/net/syslog_net/src/main.c

@@ -10,6 +10,7 @@ LOG_MODULE_REGISTER(net_syslog, LOG_LEVEL_DBG);
 #include <zephyr/kernel.h>
 
 #include <zephyr/logging/log_backend.h>
+#include <zephyr/logging/log_ctrl.h>
 
 #include <stdlib.h>
 
@@ -39,7 +40,7 @@ void main(void)
 				backend->api->init(backend);
 			}
 
-			log_backend_activate(backend, NULL);
+			log_backend_enable(backend, backend->cb->ctx, CONFIG_LOG_MAX_LEVEL);
 		}
 	}