rcu: RCU_SAVE_DYNTICK code no longer ever dead

Before RCU had unified idle, the RCU_SAVE_DYNTICK leg of the switch
statement in force_quiescent_state() was dead code for CONFIG_NO_HZ=n
kernel builds.  With unified idle, the code is never dead.  This commit
therefore removes the "if" statement designed to make gcc aware of when
the code was and was not dead.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>

kernel/rcutree.c

@@ -1747,8 +1747,6 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
 		break; /* grace period idle or initializing, ignore. */
 
 	case RCU_SAVE_DYNTICK:
-		if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK)
-			break; /* So gcc recognizes the dead code. */
 
 		raw_spin_unlock(&rnp->lock);  /* irqs remain disabled */