The mnemonic character D is used twice, for "Down" and "Restore
Defaults". Since the "restore defaults" message string is used in
multiple dialogs, changing the "down" mnemonic seems the more simple fix
(I can only find one usage for that message string).

Change-Id: I18035f6ce33dad2ce97e836dab0b50a429ff4cc1
Signed-off-by: Michael Keppler <Michael.Keppler@gmx.de>
Bug:533229