x86/cpu/topology: Provide __num_[cores|threads]_per_package

Expose properly accounted information and accessors so the fiddling with
other topology variables can be replaced.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Link: https://lore.kernel.org/r/20240213210253.120958987@linutronix.de