IB/hns: include linux/interrupt.h

I ran into this build error on linux-next:

drivers/infiniband/hw/hns/hns_roce_eq.c:477:8: error: unknown type name 'irqreturn_t'
 static irqreturn_t hns_roce_msi_x_interrupt(int irq, void *eq_ptr)
        ^~~~~~~~~~~
drivers/infiniband/hw/hns/hns_roce_eq.c: In function 'hns_roce_msi_x_interrupt':
drivers/infiniband/hw/hns/hns_roce_eq.c:485:9: error: implicit declaration of function 'IRQ_RETVAL'; did you mean 'BPF_RVAL'? [-Werror=implicit-function-declaration]
  return IRQ_RETVAL(int_work);

I have bisected this to a seemingly unrelated change that happened
to remove some indirect header inclusions. Simply including the
required header explicitly fixes the build failure.

Fixes: 09c75704

 ("xfrm: remove flow cache")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Doug Ledford <dledford@redhat.com>