x86: move ioapic code where it belongs

The commit 39928722 hacked the
ioapic resource mapping into apic.c for no good reason.
Move the code into io_apic_64.c where it belongs.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>