[emulators] Minor beautification change in MC416818 emulator.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[EMULATORS] i8259 PIC Emulator

This is first cut implemenation of i8259a compatible PIC
emulator.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Enable and Use i8259a PIC emulator for guest.

This patch enables the i8259a compatible PIC emulator. All required
wiring is added.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>