[kernel] Remove process startup_bonus to timeslice

Previously we added startup_bonus to work around a segfault happening
when we preemted a newly created process instead of letting it give up
the CPU. Bug is not longer occuring, though that makes me nervous.

src/kernel/scheduler.h

@@ -33,9 +33,6 @@ public:
 	/// How long the base timer quantum is, in us
 	static const uint64_t quantum_micros = 500;
 
-	/// How much extra time (in us) to give a process to let it load
-	static const uint64_t startup_bonus = 16000;
-
 	/// How many quanta a process gets before being rescheduled
 	static const uint16_t process_quanta = 10;