This trivial patch fixes one missing space in printk.

I already fixed it about half a year ago or more, but the change (in
arch/x86/kernel/cpu/smpboot.c at that time) didn't made into
mainline yet.
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

index 28e5f59..6c139ed 100644
Signed-off-by: NJiri Kosina <jkosina@suse.cz>