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
Merge from @xiaolu: Add exfat for modules or static mode

If you cannot write to partitions, it could be you miss SE permissions

Change-Id: I82f8e72a836d9469412e88e25e9cc2067efcb0ab
Exfat: Mount external volumes with forced context

Change-Id: Iaf3aa0d3635ae5e6b29a208a9493baf76fe58c4f
Add initial F2FS support.

Change-Id: If46bf7329a7453122a4379f9bc41cf9553426e74