x86: use bus conf in NB conf fun1 to get bus range on, on 64-bit

... so we use the same code with Quad core cpu as old opteron.

This patch is useful when acpi=off or _PXM is not there in DSDT.

Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>