Re-enable GCM and ECB modes.

Selectively reverts parts of bb845c81133c5796604dac0f8bfadd240689e543 and
4eff0f302729da0a7bd87847a5ba2ed155875d9b.

Kconfig: ECRYPT_FS select CRYPTO_GCM

Switch crypt_stat's tfm to crypto_tfm type

Attempt abstract tfm using direct casts

Completed casting work.

No longer crash, but now suffer EBADMSG.

Adding auth extents for GCM-enabled ecryptfs

Mark all the places where callers need to change.

Reduce stack size.

Write data correctly.

Close but it still fails.

Add More Debugging output.

Print more data.

Updated and added more logging.

Change size when decrypting GCM

Remove a lot of debug output.

Remove debug output.

Remvoe more debug output.

Removing comments for Zameer

Remove hard coded 16.

More cleanup.

Add documentation.

cipher_code -> cipher_mode_code.

Document flag.

Remove ECB Mode.