Setting the m_enabled variable to true or false can help
with monitoring the IRQHandler object(s) later, and there's no good
reason to have an if-else statement in those methods anyway.
Now we don't send raw numbers, but we let the IRQController object to
figure out the correct IRQ number.
This helps in a situation when we have 2 or more IOAPICs, so if IOAPIC
1 is assigned for IRQs 0-23 and IOAPIC 2 is assigned for IRQs 24-47,
if an IRQHandler of IRQ 25 invokes disable() for example, it will call
his responsible IRQController (IOAPIC 2), and the IRQController will
subtract the IRQ number with his assigned offset, and the result is that
the second redirection entry in IOAPIC 2 will be masked.
The IRQController object is RefCounted, and is shared between the
InterruptManagement class & IRQ handlers' classes.
IRQHandler, SharedIRQHandler & SpuriousInterruptHandler classes
use a responsible IRQ controller directly instead of calling
InterruptManagement for disable(), enable() or eoi().
Also, the initialization process of InterruptManagement is
simplified, so it doesn't rely on an ACPI parser to be initialized.
