Remove usages of LPU.savedPatternExists

The correct method to call is isLockPatternEnabled, which
also checks whether we've actually selected a pattern.

Also removes the code for the obsolete pattern enabled setting.

Bug: 18931518
Change-Id: I6f369eb60f8f6bb1e33384cd06534c713ab52e79

src/com/android/settings/ChooseLockSettingsHelper.java

@@ -95,7 +95,7 @@ public final class ChooseLockSettingsHelper {
      */
     private boolean confirmPattern(int request, CharSequence message,
                                    CharSequence details, boolean returnCredentials) {
-        if (!mLockPatternUtils.isLockPatternEnabled() || !mLockPatternUtils.savedPatternExists()) {
+        if (!mLockPatternUtils.isLockPatternEnabled()) {
             return false;
         }
         final Intent intent = new Intent();