Request based dm-crypt

dm-crypt provides bios based device mapper module. dm-crypt
operates on packets with 512 bytes size which is not effiicent
way for HW based crypto blocks. dm-req-crypt is developed to
address this. dm-req-crypt works on requests which carry upto
512KB of data for unmerged requests.

Signed-off-by: Dinesh K Garg <dineshg@codeaurora.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
dm: updating crypto algorithm used by dm-req-crypt

dm-req-crypt uses AES-XTS algorithm implemented by HW crypto
engine. Crypto driver renamed the aes-xts algorithm to avoid
conflict with SW based implementation of AES-XTS. dm-req-crypt
must use the new name for AES-XTS provided by crypto driver.

Signed-off-by: Dinesh K Garg <dineshg@codeaurora.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
dm: Adding support of AES 256 bits in dm-req-crypt

dm-req-crypt currently uses AES 128 bit. Updating dm-req-crypt
to use AES 256 bit instead.

Signed-off-by: Dinesh K Garg <dineshg@codeaurora.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
dm: Clean up dm-req-crypt

dm-req-crypt defines optional functions from device mapper. These
functions are not required for dm-req-crypt. dm-req-crypt has few
memory de-allocation issues. This change removes unnecessary
functions and fixes memory deallocation issues as well.

Signed-off-by: Dinesh K Garg <dineshg@codeaurora.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>