Remove the wrapper macros IRQ_DEST_MODE and IRQ_DELIVERY_MODE.

The typical 32-bit and the 64-bit build all dereference via the genapic,
so it's pointless to hide that indirection via these ugly macros.

Furthermore, it also obscures subarchitecture details.

So replace it with apic->irq_dest_mode / etc. accesses.
Signed-off-by: NIngo Molnar <mingo@elte.hu>