Git: Avoid duplicate check for modified files

Change-Id: I05e09434944706a61cc079c30d37309eea5019f5
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>

src/plugins/git/gitplugin.cpp

@@ -748,8 +748,6 @@ void GitPlugin::undoFileChanges(bool revertStaging)
 
 void GitPlugin::undoUnstagedFileChanges()
 {
-    if (!DocumentManager::saveAllModifiedDocuments())
-        return;
     undoFileChanges(false);
 }