Kernel: Refactor TimeQueue::add_timer to use timeval

The current API of add_timer makes it hard to use as
you are forced to do a bunch of time arithmetic at the
caller. Ideally we would have overloads for common time
types like timespec or timeval to keep the API as straight
forward as possible. This change moves us in that direction.

While I'm here, we should really also use the machines actual
ticks per second, instead of the OPTIMAL_TICKS_PER_SECOND_RATE.

Kernel/TimerQueue.cpp

@@ -28,6 +28,7 @@
 #include <AK/NonnullOwnPtr.h>
 #include <AK/OwnPtr.h>
 #include <Kernel/Scheduler.h>
+#include <Kernel/Time/TimeManagement.h>
 #include <Kernel/TimerQueue.h>
 
 namespace Kernel {
@@ -41,9 +42,14 @@ TimerQueue& TimerQueue::the()
     return *s_the;
 }
 
+TimerQueue::TimerQueue()
+{
+    m_ticks_per_second = TimeManagement::the().ticks_per_second();
+}
+
 u64 TimerQueue::add_timer(NonnullOwnPtr<Timer>&& timer)
 {
-    ASSERT(timer->expires > g_uptime);
+    ASSERT(timer->expires >= g_uptime);
 
     timer->id = ++m_timer_id_count;
 
@@ -58,10 +64,10 @@ u64 TimerQueue::add_timer(NonnullOwnPtr<Timer>&& timer)
     return m_timer_id_count;
 }
 
-u64 TimerQueue::add_timer(u64 duration, TimeUnit unit, Function<void()>&& callback)
+u64 TimerQueue::add_timer(timeval& deadline, Function<void()>&& callback)
 {
     NonnullOwnPtr timer = make<Timer>();
-    timer->expires = g_uptime + duration * unit;
+    timer->expires = g_uptime + seconds_to_ticks(deadline.tv_sec) + microseconds_to_ticks(deadline.tv_usec);
     timer->callback = move(callback);
     return add_timer(move(timer));
 }