dtc: Use noinput flex option for convert-dtsv0 to remove warning

[Jon Loeliger]

> The convert-dtsv0 lexer doesn't use lex's input() macro/function.
> This can result in "defined but not used" warnings.  This patch uses
> flex's noinput option to prevent this warning (as we already do for
> dtc-lexer.l).
> 
> Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

Applied.

Thanks,
jdl