Fixed NPE in canAddMoreManagedProfiles

We can use the command 'adb shell pm create-user --profileOf -10000
--managed TestProfile_12345678' to reproduce the problem.

Signed-off-by: yuanhao <yuanhao@xiaomi.com>

services/core/java/com/android/server/pm/UserManagerService.java

@@ -1443,7 +1443,7 @@ public class UserManagerService extends IUserManager.Stub {
         }
         synchronized(mUsersLock) {
             UserInfo userInfo = getUserInfoLU(userId);
-            if (!userInfo.canHaveProfile()) {
+            if (userInfo == null || !userInfo.canHaveProfile()) {
                 return false;
             }
             int usersCountAfterRemoving = getAliveUsersExcludingGuestsCountLU()