rcu: Remove typecheck() from RCU locking wrapper functions

Because raw_spin_lock_irqsave() and raw_spin_unlock_irqrestore()
both do typecheck() on their flags argument, there is no point in
duplicating this check in raw_spin_lock_irqsave_rcu_node() and
raw_spin_unlock_irqrestore_rcu_node().  This commit therefore saves
a few lines by removing this duplicated check.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>