idpf: fix idpf_vc_core_init error path

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

idpf: fix idpf_vc_core_init error path

In an event where the platform running the device control plane

is rebooted, reset is detected on the driver. It releases

all the resources and waits for the reset to complete. Once the

reset is done, it tries to build the resources back. At this

time if the device control plane is not yet started, then

the driver timeouts on the virtchnl message and retries to

establish the mailbox again.

In the retry flow, mailbox is deinitialized but the mailbox

workqueue is still alive and polling for the mailbox message.

This results in accessing the released control queue leading to

null-ptr-deref. Fix it by unrolling the work queue cancellation

and mailbox deinitialization in the reverse order which they got

initialized.