idpf: fix error handling in the init_task on load

In the Linux kernel, the following vulnerability has been resolved:

idpf: fix error handling in the init_task on load

If the init_task fails during a driver load, we end up without vports and
netdevs, effectively failing the entire process. In that state a
subsequent reset will result in a crash as the service task attempts to
access uninitialized resources. Following trace is from an error in the
init_task where the CREATE_VPORT (op 501) is rejected by the FW:

[40922.763136] idpf 0000:83:00.0: Device HW Reset initiated
[40924.449797] idpf 0000:83:00.0: Transaction failed (op 501)
[40958.148190] idpf 0000:83:00.0: HW reset detected
[40958.161202] BUG: kernel NULL pointer dereference, address: 00000000000000a8
...
[40958.168094] Workqueue: idpf-0000:83:00.0-vc_event idpf_vc_event_task [idpf]
[40958.168865] RIP: 0010:idpf_vc_event_task+0x9b/0x350 [idpf]
...
[40958.177932] Call Trace:
[40958.178491] <TASK>
[40958.179040] process_one_work+0x226/0x6d0
[40958.179609] worker_thread+0x19e/0x340
[40958.180158] ? __pfx_worker_thread+0x10/0x10
[40958.180702] kthread+0x10f/0x250
[40958.181238] ? __pfx_kthread+0x10/0x10
[40958.181774] ret_from_fork+0x251/0x2b0
[40958.182307] ? __pfx_kthread+0x10/0x10
[40958.182834] ret_from_fork_asm+0x1a/0x30
[40958.183370] </TASK>

Fix the error handling in the init_task to make sure the service and
mailbox tasks are disabled if the error happens during load. These are
started in idpf_vc_core_init(), which spawns the init_task and has no way
of knowing if it failed. If the error happens on reset, following
successful driver load, the tasks can still run, as that will allow the
netdevs to attempt recovery through another reset. Stop the PTP callbacks
either way as those will be restarted by the call to idpf_vc_core_init()
during a successful reset.