net: hns3: Changes required in PF mailbox to support VF reset

PF needs to assert the VF reset when it receives the request to
reset from VF. After receiving request PF ackknowledges the
request by replying back MBX_ASSERTING_RESET message to VF.
VF then goes to pending state and wait for hardware to complete
the reset.

This patch contains code to handle the received VF message, inform
the VF of assertion and reset the VF using cmdq interface.

Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>