dev,arch-x86: Make the I8042 reset settings more realistic.

When powered on, the "passed self test" bit should not be set. It should
only be set once the I8042 has actually been told to do a self test.
Also the mouse and keyboard should be disabled. With them disabled their
interrupts won't matter, but we might as well leave those disabled as
well.

Change-Id: Ief1ab30365a0a8ea0a116e52c16dcccf441515ec
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/55805
Reviewed-by: Matthew Poremba <matthew.poremba@amd.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/dev/x86/i8042.cc

@@ -55,13 +55,11 @@ X86ISA::I8042::I8042(const Params &p)
     fatal_if(!mouse, "The i8042 model requires a mouse instance");
     fatal_if(!keyboard, "The i8042 model requires a keyboard instance");
 
-    statusReg.passedSelfTest = 1;
-    statusReg.commandLast = 1;
     statusReg.keyboardUnlocked = 1;
 
     commandByte.convertScanCodes = 1;
-    commandByte.passedSelfTest = 1;
-    commandByte.keyboardFullInt = 1;
+    commandByte.disableMouse = 1;
+    commandByte.disableKeyboard = 1;
 
     for (int i = 0; i < p.port_keyboard_int_pin_connection_count; i++) {
         keyboardIntPin.push_back(new IntSourcePin<I8042>(