kernel/rcu/tree.c: Fix kernel-doc warnings

Fix kernel-doc warning:

../kernel/rcu/tree.c:959: warning: Excess function parameter 'irq' description in 'rcu_nmi_enter'

Fixes: cf7614e ("rcu: Refactor rcu_{nmi,irq}_{enter,exit}()")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/tree.c

@@ -954,7 +954,6 @@ void __rcu_irq_enter_check_tick(void)
 
 /**
  * rcu_nmi_enter - inform RCU of entry to NMI context
- * @irq: Is this call from rcu_irq_enter?
  *
  * If the CPU was idle from RCU's viewpoint, update rdp->dynticks and
  * rdp->dynticks_nmi_nesting to let the RCU grace-period handling know