add kernel multi thread example

Add kernel multi thread example based on the user space example

Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com>
use proper get cpu routine

Replace smp_processor_id by get_cpu or raw_smp_processor_id
according to the context and preemtion requirement

Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com>