x86, VisWS: turn into generic arch, copy visws files

copy arch/x86/mach-visws/setup_visws.c, apic_visws.c and traps_visws.c
files to arch/x86/kernel/, in preparation of the switchover to a
non-subarch setup for VISWS.

Signed-off-by: Ingo Molnar <mingo@elte.hu>