HINIC has a mailbox for PF-VF communication and the VF driver
could send port control command to PF driver via mailbox.

The control command only can be set to register in PF,
so add support in PF driver for VF PMD driver control
command when VF PMD driver work with linux PF driver.

Then, no need to add handlers to nic_vf_cmd_msg_handler[],
because the host driver just forwards it to the firmware.
Actually the firmware works on a coprocessor MGMT_CPU(inside the NIC)
which will recv and deal with these commands.
Signed-off-by: Cai Huoqing <cai.huoqing@linux.dev>
Signed-off-by: David S. Miller <davem@davemloft.net>