Refactor: make makeGen local

No need for KeyUtil to know how to make a KeyGeneration, it's cleaner
if each module handles it separately. Also, create a CryptoOptions
structure to track metadata encryption options, and simplify legacy
cipher/option handling.

Test: Treehugger
Bug: 147814592
Change-Id: I740063882914097329ff72348d0c0855c26c7aab
diff --git a/cryptfs.cpp b/cryptfs.cpp
index 04497b0..da748fd 100644
--- a/cryptfs.cpp
+++ b/cryptfs.cpp
@@ -322,7 +322,7 @@
 }
 
 const KeyGeneration cryptfs_get_keygen() {
-    return makeGen(get_crypto_type());
+    return KeyGeneration{get_crypto_type().get_keysize(), true, false};
 }
 
 /* Should we use keymaster? */