mmc: sdhci-iproc: define MMC caps in platform data

This patch moves the definition of the MMC capabilities
from the probe function into iproc platform data. After
that we are able to add support for another platform more
easily.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Suggested-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Scott Branden <sbranden@broadcom.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>