LockSettingsService: remove TODO for getCredentialTypeInternal()

The TODO for getCredentialTypeInternal() was added by ag/9569544
("Introduce Lockscreen PIN credential as first-class citizen"), which
predated ag/16692269 ("Add a binder cache to
ILockSettings#getCredentialType").  As the latter change effectively
addressed the TODO, remove the TODO.

Test: N/A
Change-Id: Ia9a33053f9e0db030bfd4272c2c4318278f896a4

services/core/java/com/android/server/locksettings/LockSettingsService.java

@@ -1317,7 +1317,6 @@ public class LockSettingsService extends ILockSettings.Stub {
         return getCredentialTypeInternal(userId);
     }
 
-    // TODO: this is a hot path, can we optimize it?
     /**
      * Returns the credential type of the user, can be one of {@link #CREDENTIAL_TYPE_NONE},
      * {@link #CREDENTIAL_TYPE_PATTERN}, {@link #CREDENTIAL_TYPE_PIN} and