x86-64: Eliminate dead ia32 syscall handlers

None of the three routines being removed here was actually
hooked up anywhere, so they all represented dead code.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4FA947FE020000780008247F@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>