Kernel/Interrupts: Move PCIIRQHandler => PCI::IRQHandler

This class is part of the PCI code so let's move it to the PCI namespace
like other handling code parts of the PCI bus.

Kernel/Devices/Audio/IntelHDA/InterruptHandler.cpp

@@ -10,7 +10,7 @@
 namespace Kernel::Audio::IntelHDA {
 
 InterruptHandler::InterruptHandler(Controller& controller)
-    : PCIIRQHandler(controller, controller.device_identifier().interrupt_line().value())
+    : PCI::IRQHandler(controller, controller.device_identifier().interrupt_line().value())
     , m_controller(controller)
 {
     enable_irq();