fix: remove check for root volume device name on create

[AverageMarcus]

What type of PR is this?

/kind bug

What this PR does / why we need it:

clusterctl move currently fails if trying to move an AWSMachinePool that have it's rootVolume already populated.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #3624

Special notes for your reviewer:

From what I can tell, the RootVolume device name is actually retrieved from the AMI image and the value in the Spec isn't used (only populated after creating).

See:

cluster-api-provider-aws/pkg/cloud/services/ec2/instances.go

Lines 926 to 942 in 7440d3e

	func (s *Service) checkRootVolume(rootVolume *infrav1.Volume, imageID string) (*string, error) {
	rootDeviceName, err := s.getImageRootDevice(imageID)
	if err != nil {
	return nil, errors.Wrapf(err, "failed to get root volume from image %q", imageID)
	}
	snapshotSize, err := s.getImageSnapshotSize(imageID)
	if err != nil {
	return nil, errors.Wrapf(err, "failed to get root volume from image %q", imageID)
	}
	if rootVolume.Size < *snapshotSize {
	return nil, errors.Errorf("root volume size (%d) must be greater than or equal to snapshot size (%d)", rootVolume.Size, *snapshotSize)
	}
	return rootDeviceName, nil
	}

Checklist:

• squashed commits
• includes documentation
• adds unit tests
• adds or updates e2e tests

[Ankitasw]

How about we log this info and not return error?

[AverageMarcus]

Good idea! Updated :)

[Ankitasw]

/test pull-cluster-api-provider-aws-e2e-blocking

[Ankitasw]

/lgtm
/approve

[k8s-ci-robot]

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