Replace most references to Keymaster with Keystore

Now that vold uses Keystore2 rather than the Keymaster HAL directly, and
also the new version of Keymaster is called "KeyMint" instead, replace
most of the references to Keymaster in vold with Keystore.

(I decided not to include the "2" in most places, as it seemed
unnecessarily precise in most places, and it would be something that
might need to keep being updated.  Only Keystore.{cpp,h} really need to
care about the version number.)

I didn't rename many things in cryptfs.cpp, as that file will be going
away soon anyway.  I also left "wait_for_keymaster" and "vdc keymaster
earlyBootEnded" as-is for now, as those are referenced outside vold.

Bug: 183669495
Change-Id: I92cd648fae09f8c9769f7cf34dbf6c6e956be4e8
diff --git a/KeyStorage.h b/KeyStorage.h
index a7e694e..cc2f549 100644
--- a/KeyStorage.h
+++ b/KeyStorage.h
@@ -31,7 +31,7 @@
   public:
     KeyAuthentication(const std::string& s) : secret{s} {};
 
-    bool usesKeymaster() const { return secret.empty(); };
+    bool usesKeystore() const { return secret.empty(); };
 
     const std::string secret;
 };
@@ -61,10 +61,10 @@
 
 bool runSecdiscardSingle(const std::string& file);
 
-// Generate wrapped storage key using keymaster. Uses STORAGE_KEY tag in keymaster.
+// Generate wrapped storage key using keystore. Uses STORAGE_KEY tag in keystore.
 bool generateWrappedStorageKey(KeyBuffer* key);
-// Export the per-boot boot wrapped storage key using keymaster.
-bool exportWrappedStorageKey(const KeyBuffer& kmKey, KeyBuffer* key);
+// Export the per-boot boot wrapped storage key using keystore.
+bool exportWrappedStorageKey(const KeyBuffer& ksKey, KeyBuffer* key);
 
 // Set a seed to be mixed into all key storage encryption keys.
 bool setKeyStorageBindingSeed(const std::vector<uint8_t>& seed);