net: hinic: fix the issue of double release MBOX callback of VF

In hinic_vf_func_init(), if VF fails to register information with PF
through the MBOX, the MBOX callback function of VF is released once. But
it is released again in hinic_init_hwdev(). Remove one.

Fixes: 7dd29ee1 ("hinic: add sriov feature support")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>