x86: Remove unused function cpu_has_ht_siblings()

It is used nowhere.

Signed-off-by: Juergen Gross <jgross@suse.com>
Link: http://lkml.kernel.org/r/1447761943-770-1-git-send-email-jgross@suse.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>