ARM: smp: Drop RCU_NONIDLE usage in cpu_die()

ARM: smp: Drop RCU_NONIDLE usage in cpu_die()

Before f7b861b7a6d9 ("arm: Use generic idle loop") ARM would kill the
CPU within the rcu idle section.  Now that the rcu_idle_enter()/exit()
pair have been pushed lower down in the idle loop this is no longer true
and so using RCU_NONIDLE here is no longer necessary and also harmful
because RCU is not actually idle at this point.

Cc: Russell King <[email protected]>
Acked-by: Paul E. McKenney <[email protected]>
Signed-off-by: Stephen Boyd <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>