Updated unit tests for symmetrix

[tdawe]

Description

PR targets the usr/spark/unit-test-improvements branch.

Increases code coverage for the symmetrix package to 92.3%

# go test -cover -race -count 1 ./...
        github.com/dell/csi-powermax/v2/pkg/symmetrix/mocks             coverage: 0.0% of statements
ok      github.com/dell/csi-powermax/v2/pkg/symmetrix   1.051s  coverage: 92.3% of statements

GitHub Issues

List the GitHub issues impacted by this PR:

GitHub Issue #

Checklist:

• Have you run format,vet & lint checks against your submission?
• Have you made sure that the code compiles?
• Did you run the unit & integration tests successfully?
• Have you maintained at least 90% code coverage?
• Have you commented your code, particularly in hard-to-understand areas
• Have you done corresponding changes to the documentation
• Did you run tests in a real Kubernetes cluster?
• Backward compatibility is not broken

How Has This Been Tested?

Unit tests were successfully run for this package.