mmc: host: Use right parameter for ext4 plus eMMC

With new encryption framework intermediate vector calculation is changed
so to support the legacy mechanism for ext4 file system use correct
parameter for data encrypt/decrypt.

Change-Id: I7921699c7a213bad7314a789d7f14a359205690f
Signed-off-by: Neeraj Soni <neersoni@codeaurora.org>