net: hns3: cleanup a format-truncation warning

In hns3_nic_init_irq(), when '*_int_idx' has more than 9 digits
and the length of netdev's name is IFNAMSIZ, the total length
of final name will be bigger the HNAE3_INT_NAME_LEN - 1, even
though '*_int_idx' will never have such large value, but the
compiler gives a format-truncation warning for this case.

So this patch just enlarges the length to avoid this warning.

Signed-off-by: Guojia Liao <liaoguojia@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>