x86: move select_idle_routine() call after detect_ht()

Move the select_idle_routine() call to after the detect_ht() call at
identify_cpu() on 64-bit.

This change is for printing the polling idle and HT enabled warning
message properly.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>