Michael Brown
b36882be34
[settings] Fix setting expansion
Commit 5fbd020 ("[settings] Display canonical setting name in output
of "show" command") introduced a regression causing all setting
expansions (e.g. "${net0/mac}") to expand to an empty string.
Fix by returning the formatted value length from
fetchf_named_setting(), as expected by the caller.
Signed-off-by: Michael Brown <mcb30@ipxe.org>