Fix hl_usleep again to undo prior fix

Fix hl_usleep to not sleep if 1ms or less is called for -- speeds things up on Windows dramatically

src/serial.c

@@ -759,7 +759,7 @@ int HAMLIB_API serial_flush(hamlib_port_t *p)
 
     timeout_save = p->timeout;
     timeout_retry_save = p->timeout_retry;
-    p->timeout = 1;
+    p->timeout = 0;
     p->timeout_retry = 0;
 
     do

src/sleep.c

@@ -52,6 +52,8 @@ extern "C" {
 int hl_usleep(rig_useconds_t usec)
 {
     int retval = 0;
+    //rig_debug(RIG_DEBUG_ERR, "%s: usec=%ld\n", __func__, usec);
+    if (usec <= 1000) return 0; // dont' sleep if only 1ms is requested -- speeds things up on Windows
 
     while (usec > 1000000)
     {
@@ -63,7 +65,7 @@ int hl_usleep(rig_useconds_t usec)
 #ifdef HAVE_NANOSLEEP
     struct timespec t, tleft;
     t.tv_sec = usec/1e6;
-    t.tv_nsec = (usec - (t.tv_sec*1e6)) / 1e3;
+    t.tv_nsec = (usec - (t.tv_sec*1e6)) * 1e3;
     return nanosleep(&t, &tleft);
 #else
     return usleep(usec);