x86/apic: Finish removing unused callbacks

x86/apic: Finish removing unused callbacks

The ->cpu_mask_to_apicid() and ->vector_allocation_domain() callbacks are
now unused, so remove them.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 024a427a7b04 ("x86/apic: Remove unused callbacks")
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1803251403540.80485@chino.kir.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>