tools: acrn-crashlog: fix format-security warning

We will get the following warning when build acrn. This patch fix it.
No functional change.

In file included from log_sys.c:8:0:
log_sys.c: In function ‘do_log’:
log_sys.c:44:26: warning: format not a string literal and no format arguments [-Wformat-security]
  sd_journal_print(level, log);
                          ^

Signed-off-by: Kaige Fu <kaige.fu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>

tools/acrn-crashlog/common/log_sys.c

@@ -45,5 +45,5 @@ void do_log(const int level,
 	log[sizeof(log) - 1] = 0;
 	va_end(args);
 
-	sd_journal_print(level, log);
+	sd_journal_print(level, "%s", log);
 }