Adding support of dm-req-crypt

Currently Android provides disk encryption support using dm-crypt
which is based on bios. dm-crypt uses 512 bytes packet size for
crypto operations. While 512 bytes size packet is ok for SW based
disk encryption, it is inefficient for HW based crypto engines.
dm-req-crypt is similar to dm-crypt except it uses block requests
rathe bios for crypto operations. block requests when unpacked
carries data upto 512KB. Hence, HW based crypto engine can be used
more efficiently.

Change-Id: Ic541d4d1b9db4ce32465e30c5f25619a80975767
Create disk encryption key before framework start

HW based disk encryption creates key in secure side. Key creation
can take sometime to create the key securely. If framework is
started before creating the key, it is possible that framework
requests service from secure side. Secure side can serve mostly one
request at a time. Secure side may reject framework request if key
creation request is still going on. This may cause problem in the
system

Change-Id: I5480ab72a37c02532218a18faaba598a824589fd