Patch from Andrey Panin <pazke@orbita1.ru>

I'm here again, starting another hopeless attempt to submmit
visws subarch support for 2.5. This series of patches was tested
by me and brave people from linux-visws-devel mailing list and
our beloved workstations seem to work well under 2.5.xx.

This patch moves enable_NMI_through_LVT0() function from io_apic.c
to apic.c to allow SMP kernel build without io_apic.c included.