binman: Fix up removal of temporary directories

At present 'make check' leaves some temporary directories around. Part of
this is because we call tools.PrepareOutputDir() twice in some cases,
without calling tools.FinaliseOutputDir() in between.

Fix this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/dtoc/test_fdt.py b/tools/dtoc/test_fdt.py
index d259702..2e6febe 100755
--- a/tools/dtoc/test_fdt.py
+++ b/tools/dtoc/test_fdt.py
@@ -60,7 +60,7 @@
 
     @classmethod
     def tearDownClass(cls):
-        tools._FinaliseForTest()
+        tools.FinaliseOutputDir()
 
     def setUp(self):
         self.dtb = fdt.FdtScan('tools/dtoc/dtoc_test_simple.dts')
@@ -128,7 +128,7 @@
 
     @classmethod
     def tearDownClass(cls):
-        tools._FinaliseForTest()
+        tools.FinaliseOutputDir()
 
     def setUp(self):
         self.dtb = fdt.FdtScan('tools/dtoc/dtoc_test_simple.dts')
@@ -209,7 +209,7 @@
 
     @classmethod
     def tearDownClass(cls):
-        tools._FinaliseForTest()
+        tools.FinaliseOutputDir()
 
     def setUp(self):
         self.dtb = fdt.FdtScan('tools/dtoc/dtoc_test_simple.dts')
@@ -427,6 +427,10 @@
     def setUpClass(cls):
         tools.PrepareOutputDir(None)
 
+    @classmethod
+    def tearDownClass(cls):
+        tools.FinaliseOutputDir()
+
     def setUp(self):
         self.dtb = fdt.FdtScan('tools/dtoc/dtoc_test_simple.dts')
         self.node = self.dtb.GetNode('/spl-test')