mvebu_mmc: Driver addition

mvebu_mmc: Driver addition

In function mvebu_mmc_write notice command timeout. It is possible that a
command is done, but a timeout occurred.

Enable timeout in set bus function.

Set window registers. Without that I could not use the driver on a Kirkwood
88F6282 SoC.

Set high capacity and 52MHz driver feature.

Signed-off-by: Mario Schuknecht <mario.schuknecht@dresearch-fe.de>
Reviewed-by: Stefan Roese <sr@denx.de>
Acked-by: Pantelis Antoniou <panto@antoniou-consulting.com>