ice: msm: Encrypt only userdata

During the device encryption the vold daemon sends sectors
to drivers. Encryption has to be done only for the data
partition sectors which are passed from user space.

Change-Id: I701359a11cfb1574192badb23b92fec5bf4ad488
Signed-off-by: AnilKumar Chimata <anilc@codeaurora.org>