conversation: adjust list margin to text entry size

Change-Id: Iac173c0c68c8db10600b1b2181320c9402cb78cc
diff --git a/ring-android/app/src/main/res/values/dimens.xml b/ring-android/app/src/main/res/values/dimens.xml
index ccdda6c..db4a380 100644
--- a/ring-android/app/src/main/res/values/dimens.xml
+++ b/ring-android/app/src/main/res/values/dimens.xml
@@ -25,6 +25,7 @@
     <dimen name="padding_large">16dp</dimen>
 
     <dimen name="radius_message_input">16dp</dimen>
+    <dimen name="margin_message_input">16dp</dimen>
 
     <dimen name="activity_horizontal_margin">32dp</dimen>
     <dimen name="activity_vertical_margin">16dp</dimen>