rcu: Make TASKS_RUDE_RCU select IRQ_WORK

The TASKS_RUDE_RCU does not select IRQ_WORK, which can result in build
failures for kernels that do not otherwise select IRQ_WORK.  This commit
therefore causes the TASKS_RUDE_RCU Kconfig option to select IRQ_WORK.

Reported-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>