x86/apic: Replaces spaces with tabs to fix indentation in apic.c

Fix spaces vs. tabs indentation in apic.c to make enhancing the test
slightly less painful.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221001011301.2077437-3-seanjc@google.com