net: enetc: allocate vf_state during PF probes
In the Linux kernel, the following vulnerability has been resolved:

net: enetc: allocate vf_state during PF probes

In the previous implementation, vf_state is allocated memory only when VF
is enabled. However, net_device_ops::ndo_set_vf_mac() may be called before
VF is enabled to configure the MAC address of VF. If this is the case,
enetc_pf_set_vf_mac() will access vf_state, resulting in access to a null
pointer. The simplified error log is as follows.

root@ls1028ardb:~# ip link set eno0 vf 1 mac 00:0c:e7:66:77:89
[  173.543315] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004
[  173.637254] pc : enetc_pf_set_vf_mac+0x3c/0x80 Message from sy
[  173.641973] lr : do_setlink+0x4a8/0xec8
[  173.732292] Call trace:
[  173.734740]  enetc_pf_set_vf_mac+0x3c/0x80
[  173.738847]  __rtnl_newlink+0x530/0x89c
[  173.742692]  rtnl_newlink+0x50/0x7c
[  173.746189]  rtnetlink_rcv_msg+0x128/0x390
[  173.750298]  netlink_rcv_skb+0x60/0x130
[  173.754145]  rtnetlink_rcv+0x18/0x24
[  173.757731]  netlink_unicast+0x318/0x380
[  173.761665]  netlink_sendmsg+0x17c/0x3c8