mmc: card: Adding support for sanitize in eMMC 4.5

This feature delete the unmap memory region of the eMMC card,
by writing to a specific register in the EXT_CSD
unmap region is the memory region that were previously deleted
(by erase, trim or discard operation)

Change-Id: I7f1df8e87fb782979fd90e064eca00704caca54b
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>