x86/apic: Fix 32-bit APIC initialization for extended Intel Families

APIC detection is currently limited to a few specific Families and will
not match the upcoming Families >=18.

Extend the check to include all Families 6 or greater. Also convert it
to a VFM check to make it simpler.

Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20250219184133.816753-2-sohil.mehta@intel.com