Settings: add logpersist kernel only selection

Bug: 28813587
Bug: 28936216
Bug: 29831823
Change-Id: I9bfbb2717c2d4d39bfda6b92221a38985a4f4973
diff --git a/src/com/android/settings/DevelopmentSettings.java b/src/com/android/settings/DevelopmentSettings.java
index 4335817..6d07e41 100644
--- a/src/com/android/settings/DevelopmentSettings.java
+++ b/src/com/android/settings/DevelopmentSettings.java
@@ -1574,7 +1574,9 @@
         int index = 0;
         if (currentValue.equals(SELECT_LOGPERSIST_PROPERTY_SERVICE)) {
             index = 1;
-            if (!currentBuffers.equals("all") &&
+            if (currentBuffers.equals("kernel")) {
+                index = 3;
+            } else if (!currentBuffers.equals("all") &&
                     !currentBuffers.contains("radio") &&
                     currentBuffers.contains("security") &&
                     currentBuffers.contains("kernel")) {