Don't reset the keystore during password change

There is absolutely no advantage to doing this.

Bug: 18817878
Change-Id: Ibb386696e67c316e65f53c28f9249ef2a2a48db6

src/com/android/settings/ChooseLockPassword.java

@@ -432,7 +432,6 @@ public class ChooseLockPassword extends SettingsActivity {
             } else if (mUiStage == Stage.NeedToConfirm) {
                 if (mFirstPin.equals(pin)) {
                     boolean wasSecureBefore = mLockPatternUtils.isSecure();
-                    mLockPatternUtils.clearLock();
                     final boolean required = getActivity().getIntent().getBooleanExtra(
                             EncryptionInterstitial.EXTRA_REQUIRE_PASSWORD, true);
                     mLockPatternUtils.setCredentialRequiredToDecrypt(required);