md: add mem_dump_mult/single_column()

Current mem_dump() showed memory as multi column,
but single dump function was useful.
This patch add mem_dump_single_column().

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
md: add -c option

-c : it dump memory on one column

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
md: add -s option

-s : silence memory dump

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>