No longer upgrade password quality based on keystore

Keystore no longer requires a password to operate and only deletes
encrypted at rest entries when the user removes their password, so
blocking password downgrade is no longer required.

Bug: 20764363
Change-Id: I6f06acc71a4165282985082203ae1194491844c7
diff --git a/src/com/android/settings/ChooseLockGeneric.java b/src/com/android/settings/ChooseLockGeneric.java
index 7aa1053..317d372 100644
--- a/src/com/android/settings/ChooseLockGeneric.java
+++ b/src/com/android/settings/ChooseLockGeneric.java
@@ -292,7 +292,6 @@
         /** increases the quality if necessary */
         private int upgradeQuality(int quality) {
             quality = upgradeQualityForDPM(quality);
-            quality = upgradeQualityForKeyStore(quality);
             return quality;
         }
 
@@ -305,15 +304,6 @@
             return quality;
         }
 
-        private int upgradeQualityForKeyStore(int quality) {
-            if (!mKeyStore.isEmpty()) {
-                if (quality < CredentialStorage.MIN_PASSWORD_QUALITY) {
-                    quality = CredentialStorage.MIN_PASSWORD_QUALITY;
-                }
-            }
-            return quality;
-        }
-
         /***
          * Disables preferences that are less secure than required quality. The actual
          * implementation is in disableUnusablePreferenceImpl.