rcu: Move code to apply callback-numbering simplifications

The addition of callback numbering allows combining the detection of the
ends of old grace periods and the beginnings of new grace periods.  This
commit moves code to set the stage for this combining.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Git-commit: 6eaef633d77f50f031dd355ff5f91aaa1aaf9885
Signed-off-by: Kishan Kumar <kishank@codeaurora.org>