Remove unnecessary android:codes attribute

If there is no android:codes specified, the first character of
keyLabel's code point will be used instead.

Also introduce readable codes as @integer/key_XXX resources

Bug: 2973749
Change-Id: If9021ca35f9a7b922817e2099186fce0cd993652
diff --git a/java/res/values/keycodes.xml b/java/res/values/keycodes.xml
index 3f03dd6..9dded50 100644
--- a/java/res/values/keycodes.xml
+++ b/java/res/values/keycodes.xml
@@ -19,6 +19,12 @@
 -->
 
 <resources>
+    <integer name="key_tab">9</integer>
+    <integer name="key_return">10</integer>
+    <integer name="key_space">32</integer>
+    <integer name="key_shift">-1</integer>
+    <integer name="key_symbol">-2</integer>
+    <integer name="key_delete">-5</integer>
     <!-- Keycode for F1 (function) key. This one switches between language switch & comma/.com -->
     <integer name="key_settings">-100</integer>
     <integer name="key_f1">-103</integer>