binman: Set up 'entry' to permit full test coverage

There is a little check at the top of entry.py which decides if importlib
is available. At present this has no test coverage. To add this we will
need to import the module twice, once with importlib and once without.
In preparation for allowing a test to control the importing of this
module, remove all global imports of the 'entry' module.

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

tools/binman/ftest.py

@@ -20,7 +20,6 @@ import binman
 import cmdline
 import command
 import control
-import entry
 import fdt
 import fdt_util
 import tools
@@ -56,6 +55,9 @@ class TestFunctional(unittest.TestCase):
     """
     @classmethod
     def setUpClass(self):
+        global entry
+        import entry
+
         # Handle the case where argv[0] is 'python'
         self._binman_dir = os.path.dirname(os.path.realpath(sys.argv[0]))
         self._binman_pathname = os.path.join(self._binman_dir, 'binman')