lkdtm: fix handle_irq_event symbol for INT_HW_IRQ_EN

Function handle_IRQ_event was retired in v2.6.39 and replaced with
handle_irq_event but nobody changed it in lkdtm so INT_HW_IRQ_EN has
been broken for a while.

Fixes: 33b054b8 ("genirq: Remove handle_IRQ_event")
Signed-off-by: Travis Brown <travisb@arista.com>
Signed-off-by: Ivan Delalande <colona@arista.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>