zero out temporary arrays so SKEB will work when no vorticity damping

[pjpegion]

Description

This is a follow on fix that is needed to get Stochastic Kinetic Energy Backsckatter (SKEB) working in the hydrostatic version of the dycore.

Fixes #
This addresses issue #392

How Has This Been Tested?
Scientifically I tested on MSU's orion with a several month old code, and this week on NOAA's ursa for regression test and scientific validation. In both cases, it was with the intel compiler.

Checklist:

Please check all whether they apply or not

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[gspetro-NOAA]

Testing completed successfully for WM parent PR 2997. We are ready for a code manager to merge this PR.