logging: fix syslog identifier for NetworkManager

We no longer define G_LOG_DOMAIN differently for the libraries and
applications. Instead, the use now all "nm".

However, that also changes the syslog identifier for NetworkManager
core. That is undesirable. Change it back to "NetworkManager".

Fixes: 341b6e0704 ('all: change G_LOG_DOMAIN to "nm"')

src/libnm-log-core/nm-logging.c

@@ -126,7 +126,7 @@ static union {
             /* nm_logging_setup ("INFO", LOGD_DEFAULT_STRING, NULL, NULL); */
             .log_level         = LOGL_INFO,
             .log_backend       = LOG_BACKEND_GLIB,
-            .syslog_identifier = "SYSLOG_IDENTIFIER=" G_LOG_DOMAIN,
+            .syslog_identifier = "SYSLOG_IDENTIFIER=NetworkManager",
             .prefix            = "",
         },
 };