awful.menu: remove superfluous return true from keygrabber's callback

Returning true from the callback to `keygrabber` is no longer necessary to
continue grabbing the keyboard.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>
Signed-off-by: Uli Schlachter <psychon@znc.in>

lib/awful/menu.lua.in

@@ -194,9 +194,7 @@ end
 
 
 local function grabber(mod, key, event)
-    if event == "release" then
-       return true
-    end
+    if event ~= "press" then return end
 
     local sel = cur_menu.sel or 0
     if util.table.hasitem(menu_keys.up, key) then
@@ -216,8 +214,6 @@ local function grabber(mod, key, event)
     else
         check_access_key(cur_menu, key)
     end
-
-    return true
 end