rcu: Add lockdep_assert_irqs_disabled() to rcu_sched_clock_irq() and callees

rcu: Add lockdep_assert_irqs_disabled() to rcu_sched_clock_irq() and callees

[ Upstream commit a649d25dcc671a33b9cc3176411920fdc5fbd98e ]

This commit adds a number of lockdep_assert_irqs_disabled() calls
to rcu_sched_clock_irq() and a number of the functions that it calls.
The point of this is to help track down a situation where lockdep appears
to be insisting that interrupts are enabled within these functions, which
should only ever be invoked from the scheduling-clock interrupt handler.

Link: https://lore.kernel.org/lkml/20201111133813.GA81547@elver.google.com/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>