ARM: ux500: support SD cards on HREFv60 boards

Properly support the correct SDI-init sequence on the
ST-Ericsson HREFv60 and later boards in order to get
support for SD cards.

Signed-off-by: Stefan Nilsson XK <stefan.xk.nilsson@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>