Add comment for non-preempt kernel

drivers/pit.c

@@ -1,9 +1,9 @@
 #include "pit.h"
 #include "io.h"
 #include "irq.h"
+#include "klibc.h"
 #include "kthread.h"
 #include "time.h"
-#include "klibc.h"
 
 int pitSetup(unsigned int freq)
 {
@@ -21,5 +21,7 @@ struct cpu_state *pitIrqHandler(struct cpu_state *prevCpu)
 {
     __atomic_add_fetch(&jiffies, 1, __ATOMIC_RELAXED);
     kthreadOnJieffiesTick();
+    // Uncomment for non-preemptible kernel
+    // return prevCpu;
     return kthreadSwitch(prevCpu);
 }