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/binman/entry_test.py b/tools/binman/entry_test.py
index 69d85b4..a8bc938 100644
--- a/tools/binman/entry_test.py
+++ b/tools/binman/entry_test.py
@@ -14,9 +14,14 @@
 import tools
 
 class TestEntry(unittest.TestCase):
+    def setUp(self):
+        tools.PrepareOutputDir(None)
+
+    def tearDown(self):
+        tools.FinaliseOutputDir()
+
     def GetNode(self):
         binman_dir = os.path.dirname(os.path.realpath(sys.argv[0]))
-        tools.PrepareOutputDir(None)
         fname = fdt_util.EnsureCompiled(
             os.path.join(binman_dir,('test/05_simple.dts')))
         dtb = fdt.FdtScan(fname)
@@ -35,7 +40,6 @@
         global entry
         reload(entry)
         entry.Entry.Create(None, self.GetNode(), 'u-boot-spl')
-        tools._RemoveOutputDir()
         del entry
 
     def testEntryContents(self):