RDMA/hns: remove set but not used variable 'irq_num'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/infiniband/hw/hns/hns_roce_hw_v2.c: In function hns_roce_v2_cleanup_eq_table:
drivers/infiniband/hw/hns/hns_roce_hw_v2.c:5920:6:
 warning: variable irq_num set but not used [-Wunused-but-set-variable]

It is not used since
commit 33db6f94 ("RDMA/hns: Refactor eq table init for hip08")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20190731073748.17664-1-yuehaibing@huawei.comSigned-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hns/hns_roce_hw_v2.c

@@ -5917,12 +5917,10 @@ static int hns_roce_v2_init_eq_table(struct hns_roce_dev *hr_dev)
 static void hns_roce_v2_cleanup_eq_table(struct hns_roce_dev *hr_dev)
 {
 	struct hns_roce_eq_table *eq_table = &hr_dev->eq_table;
-	int irq_num;
 	int eq_num;
 	int i;
 
 	eq_num = hr_dev->caps.num_comp_vectors + hr_dev->caps.num_aeq_vectors;
-	irq_num = eq_num + hr_dev->caps.num_other_vectors;
 
 	/* Disable irq */
 	hns_roce_v2_int_mask_enable(hr_dev, eq_num, EQ_DISABLE);