sched: move pCPU initialization in a helper

sched: move pCPU initialization in a helper

That will turn out useful in following patches, where such
code will need to be called more than just once. Create an
helper now, and move the code there, to avoid mixing code
motion and functional changes later.

In Credit2, some style cleanup is also done.

No functional change intended.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Reviewed-by: George Dunlap <george.dunlap@eu.citrix.com>