x86/apic: Cleanup delivery mode defines

The enum ioapic_irq_destination_types and the enumerated constants starting
with 'dest_' are gross misnomers because they describe the delivery mode.

Rename then enum and the constants so they actually make sense.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201024213535.443185-6-dwmw2@infradead.org