net/hns3: fix mailbox wait time

net/hns3: fix mailbox wait time

The mailbox wait time can be specified at runtime. But the variable that
controls this time are not initialized when the variable isn't designated
or is specified as an invalid value, which will fail to initialize device
in the case where no device is bound to initialize the device.

Fixes: 2fc3e696a7f1 ("net/hns3: add runtime config for mailbox limit time")
Cc: stable@dpdk.org
Signed-off-by: Huisong Li <lihuisong@huawei.com>