binman: Run tests concurrently

At present the tests run one after the other using a single CPU. This is
not very efficient. Bring in the concurrencytest module and run the tests
concurrently, using one process for each CPU by default. A -P option
allows this to be overridden, which is necessary for code-coverage to
function correctly.

This requires fixing a few tests which are currently not fully
independent.

At some point we might consider doing this across all pytests in U-Boot.
There is a pytest version that supports specifying the number of processes
to use, but it did not work for me.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/binman/entry_test.py

@@ -13,6 +13,8 @@ import fdt
 import fdt_util
 import tools
 
+entry = None
+
 class TestEntry(unittest.TestCase):
     def setUp(self):
         tools.PrepareOutputDir(None)
@@ -38,7 +40,10 @@ class TestEntry(unittest.TestCase):
     def test2EntryImportLib(self):
         del sys.modules['importlib']
         global entry
-        reload(entry)
+        if entry:
+            reload(entry)
+        else:
+            import entry
         entry.Entry.Create(None, self.GetNode(), 'u-boot-spl')
         del entry