[IA64] Add config SCHED_SMT

[IA64] Add config SCHED_SMT

Now that we have MC/MT detection patches in, appended patch allows us to
configure MT scheduler optimizations. For now, we will this option off
by default.

There is some discussion going on lkml about setting up sched-domains
which are absolutely needed (like for example, we shouldn't setup SMT domain
for non MT processors). Once that patch goes in, we can enable this option by
default.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>