sl5500: note about SDIO

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
sl5600 status

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
sl6000 status

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>