cmdline: avoid garbage in unused fields of parsed result

cmdline: avoid garbage in unused fields of parsed result

The result buffer was not initialized before parsing, inducing garbage
in unused fields or padding of the parsed structure.

Initialize the result buffer each time before parsing.

Fixes: af75078fece3 ("first public release")
Cc: stable@dpdk.org
Signed-off-by: Xueming Li <xuemingl@mellanox.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>