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>

tools/binman/ftest.py

@@ -115,7 +115,6 @@ class TestFunctional(unittest.TestCase):
         TestFunctional._MakeInputFile('ecrw.bin', CROS_EC_RW_DATA)
         TestFunctional._MakeInputDir('devkeys')
         TestFunctional._MakeInputFile('bmpblk.bin', BMPBLK_DATA)
-        self._output_setup = False
 
         # ELF file with a '_dt_ucode_base_size' symbol
         with open(self.TestFile('u_boot_ucode_ptr')) as fd:
@@ -230,14 +229,13 @@ class TestFunctional(unittest.TestCase):
         Returns:
             Contents of device-tree binary
         """
-        if not self._output_setup:
-            tools.PrepareOutputDir(self._indir, True)
-            self._output_setup = True
+        tools.PrepareOutputDir(None)
         dtb = fdt_util.EnsureCompiled(self.TestFile(fname))
         with open(dtb) as fd:
             data = fd.read()
             TestFunctional._MakeInputFile(outfile, data)
-            return data
+        tools.FinaliseOutputDir()
+        return data
 
     def _GetDtbContentsForSplTpl(self, dtb_data, name):
         """Create a version of the main DTB for SPL or SPL