Fixes hammer upgrade

[Humonitarian]

About The Pull Request

No idea who added the hammer upgrade, but not only did they forget to test the code, noone actually noticed this bug by what I saw so far.

Why It's Good For The Game

Fixes flat top.

Testing

Not tested. Do not merge until someone tests this.

Changelog

🆑
fix: fixed flat top not giving qualities when installed
/:cl:

[Mycah142]

No one noticed because no one with half a braincell uses this tool mod seriously. It's functionally a waste as wrench, shovel, and crowbar all have hammering aspects already.

Attempts were made to give it another benefit but were shot down.

[DiaFRAME444]

#7822

Actually, you all are wrong. I had this scenario before - power shovel modded to hell with 900% speed and 30 precision. I added the flat surface, didn't really impact the stats. Suddenly I had a tool that was effectively a maxed out hammer, alongside the usual shovel qualities.

Hmmm...

[hyperioo]

I think we also need to reset switched_on_qualities and tool_qualities to their initial values in /obj/item/tool/refresh_upgrades(). Otherwise it will never be removed even if the mod goes away.