x86, visws: fix generic-ipi build

fix:

 arch/x86/kernel/built-in.o: In function `smp_intr_init':
 (.init.text+0x49e2): undefined reference to `call_function_single_interrupt'

Caused by include/asm-x86/mach-visws/entry_arch.h getting out of sync
with the include/asm-x86/mach-default/entry_arch.h file it derives from.

Copy the default file over - next step will be to simply include the default
file.

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