Clean up diskLooksUnformatted literal

[karataliu]

What this PR does / why we need it:
#16948 moved the formatAndMount function to mount_linux.go, but diskLooksUnformatted does not necessarily need to appear in mount_unsupported.go
#31515 Renames diskLooksUnformatted to getDiskFormat, but did not update the comment

This is to do the small cleanup.

Which issue this PR fixes

Special notes for your reviewer:

Release note:

[k8s-ci-robot]

Hi @karataliu. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[xiangpengzhao]

/ok-to-test
/release-note-none

[karataliu]

Ping. this change should be simple and clear.

[xiangpengzhao]

/lgtm

/assign @jingxu97
for approval. Thanks!

[karataliu]

/retest

[jingxu97]

/approve

[k8s-github-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jingxu97, karataliu, xiangpengzhao

Associated issue: 16948

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these OWNERS Files:

• pkg/util/mount/OWNERS [jingxu97]

You can indicate your approval by writing /approve in a comment
You can cancel your approval by writing /approve cancel in a comment

[fejta-bot]

/retest
This bot automatically retries jobs that failed/flaked on approved PRs (send feedback to @fejta).

Review the full test history for this PR.

[karataliu]

/retest

[fejta-bot]

/retest
This bot automatically retries jobs that failed/flaked on approved PRs (send feedback to @fejta).

Review the full test history for this PR.

[k8s-github-robot]

/test all [submit-queue is verifying that this PR is safe to merge]

[k8s-github-robot]

Automatic merge from submit-queue (batch tested with PRs 43016, 50503, 51281, 51518, 51582). If you want to cherry-pick this change to another branch, please follow the instructions here..

[k8s-ci-robot]

@karataliu: The following test failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
pull-kubernetes-e2e-gce-bazel	a6ff000	link	/test pull-kubernetes-e2e-gce-bazel

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.