drivers/storage/mmc: Add callback to execute tuning

For grunt we need to execute tuning in order to use HS200.

BRANCH=grunt
BUG=b:122244718
TEST=Made sure it compiles

Change-Id: Ifa512cb5e1621b143cadd6852c1661530f27d5c7
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/depthcharge/+/1655551
Reviewed-by: Martin Roth <martinroth@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
2 files changed