sched: remove sched_init_pdata()

sched: remove sched_init_pdata()

sched_init_pdata() is used nowhere, it can be removed. Same applies to
the .init_pdata hook of the per-scheduler interface. The last caller
has been removed with commit f855dd962523b6cb47a92037bdd28b1485141abe
("sched: add minimalistic idle scheduler for free cpus").

With the idle scheduler introduction the switch_sched hook became the
only place where new cpus get added to a normal scheduler, so the
init_pdata functionality is performed inside that hook.

Adjust some comments as well to reflect reality. While at it correct a
typo in a comment next to a modified comment.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Dario Faggioli <dfaggioli@suse.com>