Preempt counter APIs have been split out, currently, hardirq.h just
includes irq_enter/exit APIs which are not used by openvswitch at all.

So, remove the unused hardirq.h.
Signed-off-by: NYang Shi <yang.s@alibaba-inc.com>
Acked-by: NPravin B Shelar <pshelar@ovn.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: dev@openvswitch.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>