Remove device disable call

[mattcary]

/kind bug

What this PR does / why we need it:
The device disable call has been failing because a newline needed to be added to the "offline" state written to sysfs. But in testing that, we've discovered disabling devices can cause problems. From a comment that I've added into this PR:

Once a device is disabled, it's unusable, and can't be enabled unless the serial number is known. But the serial number cannot be read from the device as it's disabled. If a device is disabled in NodeUnstage, and then NodeStage is called without a NodeUnpublish & publish sequence, the disabled state of the device will cause NodeStage to fail. So this can only be used if we track the serial numbers of disabled devices in a persisent way that survives driver restarts.

Remove disable device call on node unstage. This call was producing spurious error messages and was not effective.

@pwschuurman

[mattcary]

/retest

[pwschuurman]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mattcary, pwschuurman

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[mattcary]

/retest

[mattcary]

/retest

I up'd the timeout on the e2e tests, let's see if that fixed it.