syslog: Remove the lock from syslog_default_write

to avoid the problem when is called from interrupt/signal handler

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>

drivers/syslog/syslog_channel.c

@@ -217,11 +217,7 @@ static ssize_t syslog_default_write(FAR struct syslog_channel_s *channel,
                                     FAR const char *buffer, size_t buflen)
 {
 #if defined(CONFIG_ARCH_LOWPUTC)
-  static sem_t sem = SEM_INITIALIZER(1);
-
-  nxsem_wait(&sem);
   up_puts(buffer);
-  nxsem_post(&sem);
 #endif
 
   UNUSED(channel);