rcu: Simplify association of forced quiescent states with grace periods

The force_quiescent_state() function also took a snapshot
of the ->completed field, which was as obnoxious as it was in
rcu_sched_qs() and friends.  So snapshot ->gpnum-1.

Also, since the dyntick_record_completed() and
dyntick_recall_completed() functions are now simple assignments
that are independent of CONFIG_NO_HZ, and since their names are
now misleading, get rid of them.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <12580941042308-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>