monitor: Fix WL_OUTPUT_PREFERRED_MODE comparison c'n'p error

and use a simpler expressionfor WL_OUTPUT_CURRENT_MODE

src/monitor/monitor.c

@@ -100,10 +100,10 @@ output_handle_mode (void             *data,
   if (height > self->height)
     self->height = height;
 
-  if ((flags & WL_OUTPUT_MODE_CURRENT) == 1)
+  if (flags & WL_OUTPUT_MODE_CURRENT)
     self->current_mode = self->modes->len - 1;
 
-  if ((flags & WL_OUTPUT_MODE_PREFERRED) == 1)
+  if (flags & WL_OUTPUT_MODE_PREFERRED)
     self->preferred_mode = self->modes->len - 1;
 }