[No GBP] fixes railing deconstruction giving free iron (#77953)

whoops

## About The Pull Request

i forgot to set the deconstruction values in
https://github.com/tgstation/tgstation/pull/77894
this fixes my mistake

closes https://github.com/tgstation/tgstation/issues/77952

## Changelog

🆑
fix: Railings no longer give more metal than they take
/🆑

code/game/objects/structures/railings.dm

@@ -90,8 +90,12 @@
 
 /obj/structure/railing/deconstruct(disassembled)
 	if(!(flags_1 & NODECONSTRUCT_1))
-		var/obj/item/stack/rods/rod = new /obj/item/stack/rods(drop_location(), 6)
-		transfer_fingerprints_to(rod)
+		if (istype(src,/obj/structure/railing/corner)) // Corner railings only cost 1 rod
+			var/obj/item/stack/rods/rod = new /obj/item/stack/rods(drop_location(), 1)
+			transfer_fingerprints_to(rod)
+		else
+			var/obj/item/stack/rods/rod = new /obj/item/stack/rods(drop_location(), 2)
+			transfer_fingerprints_to(rod)
 	return ..()
 
 ///Implements behaviour that makes it possible to unanchor the railing.