Remove dttdf/dttke from gravity_wave_moving_mountain

From review of https://github.com/ESCOMP/atmospheric_physics/pull/338

@peverwhee wrote:
> I imagine this is true in CAM as well, but this and dttke below don't seem to be used anywhere.
> Do we want to output TTGWSDF and TTGWSKE in the moving mountains diagnostics? If not, can we remove these variables?

@jimmielin wrote:
> I agree they're not used anywhere right now. I think some of the reasoning for leaving it as an output even though unused right now, is to allow for this possibility without requiring an atmos_phys + CAM update, in case scientists need it (as the moving mountain gw is in more active/recent development, I think.)
> I am happy to open an issue to remove this but it would require an extra CAM update and I was hoping to avoid it :-)

This requires a CAM update together when it is done