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/Net/E1000NetworkAdapter.cpp

@@ -177,7 +177,7 @@ E1000NetworkAdapter::~E1000NetworkAdapter()
 {
 }
 
-void E1000NetworkAdapter::handle_irq(RegisterState&)
+void E1000NetworkAdapter::handle_irq(const RegisterState&)
 {
     out32(REG_IMASK, 0x1);