download/coreboot: fix downloads without argument

this should download all trees:

	./download coreboot

without this patch, it doesn't

with this patch, it works

i overlooked this during earlier
refactoring. auditing revealed it.

resources/scripts/download/coreboot

@@ -60,7 +60,7 @@ fetch_coreboot_trees()
 	else
 		for board in resources/coreboot/*; do
 			[ ! -d "${board}" ] && continue
-			boards="${boards} ${board}"
+			boards="${boards} ${board##*/}"
 		done
 	fi
 	for board in ${boards}; do