While removing custom rendezvous code and switching to stop_machine,
commit 192d8857 ("x86, mtrr: use stop_machine APIs for doing MTRR
rendezvous") completely dropped mtrr setting code on !CONFIG_SMP
breaking MTRR settting on UP.

Fix it by removing the incorrect CONFIG_SMP.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NAnders Eriksson <aeriksson@fastmail.fm>
Tested-and-acked-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Acked-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>