Resolve merge conflict and enable HW FBE for ext4 fs

HW File Based Encryption (FBE) uses Crypto Engine to
encrypt the user data with unique key for each file.
File name and data both are encrypted with this feature.
 - security/pfk: New module to support per file
   encryption using CE.
 - fs/ext4: changes made to support using crypto engine
   to encyrpt the data.
Other changes made to provide support framework for per
file encryption.

Change-Id: I82b05a73b10ad8c26b0e400cdf246c67a8060f0e
Signed-off-by: Neeraj Soni <neersoni@codeaurora.org>