mmc: core: add proper be32 annotation

Annotate big endian values correctly and make sparse happy.
In mmc_app_send_scr remove scr function parameter as it was
updating card->raw_scr anyway.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>