Slightly simplify AMOLED theme definition

app/src/main/res/values/themes.xml

@@ -162,10 +162,7 @@
         <item name="colorPrimaryVariant">@color/colorPrimary</item>
     </style>
 
-    <!--==============-->
-    <!-- Amoled Theme -->
-    <!--==============-->
-    <style name="Theme.Base.Amoled" parent="Theme.Base.Dark">
+    <style name="Theme.Tachiyomi.Amoled" parent="Theme.Base.Dark">
         <item name="colorPrimary">@color/colorAmoledPrimary</item>
         <item name="colorPrimaryVariant">@color/colorAmoledPrimary</item>
         <item name="colorSurface">@color/colorAmoledPrimary</item>
@@ -180,10 +177,6 @@
         <item name="colorLibrarySelectionActive">@color/selectorColorDark</item>
     </style>
 
-    <style name="Theme.Tachiyomi.Amoled" parent="Theme.Base.Amoled">
-        <!-- Attributes specific for SDK 16 to SDK 20 -->
-    </style>
-
     <!--==============-->
     <!-- Reader Theme -->
     <!--==============-->