Fix reverting to SCHED_OTHER

This still seemed to work, but the `sched_setscheduler` would return an
error code when the priority is set to 5 for SCHED_OTHER (which is of
course not a valid value here).

src/common/utils.cpp

@@ -42,7 +42,7 @@ bool set_realtime_priority(bool sched_fifo) {
         }
     }
 
-    sched_param params{.sched_priority = 5};
+    sched_param params{.sched_priority = (sched_fifo ? 5 : 0)};
     return sched_setscheduler(0, sched_fifo ? SCHED_FIFO : SCHED_OTHER,
                               &params) == 0;
 }