Kernel: Use a const reference to RegisterState in IRQ handling

Author: https://github.com/supercomputer7
Commit: e880fe0765
Pull-request: https://github.com/SerenityOS/serenity/pull/1396
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/shannonbooth ✅

Kernel/Devices/PATAChannel.cpp

@@ -180,7 +180,7 @@ void PATAChannel::wait_for_irq()
     disable_irq();
 }
 
-void PATAChannel::handle_irq(RegisterState&)
+void PATAChannel::handle_irq(const RegisterState&)
 {
     u8 status = m_io_base.offset(ATA_REG_STATUS).in<u8>();
     if (status & ATA_SR_ERR) {