ARM: 7422/1: mmc: mmci: Allocate platform memory during Device Tree boot

When booting with Device Tree enabled, platform specific information
is gathered by parsing the DT binary. Platform data is subsequently
populated with the result. The memory required for this is not
automatically allocated during Device Tree boot, so we'll do it here
instead.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>