mmc: fixes for eMMC v4.5 sanitize operation

mmc: fixes for eMMC v4.5 sanitize operation

commit 283028122db37621b124f079ca8eae5b64807ad4 upstream.

eMMC v4.5 sanitize operation erases all copies of unmapped
data.  However trim or erase operations must be used first
to unmap the required sectors.  That was not being done.

Fixes apply to linux 3.2 on.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>