binman: Rename tests to ftest

At present these tests use the same filename as patman. This adds
confusion when running all tests, since error messages look very similar.
In fact binman tries to run the wrong tests at present.

Rename the tests.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/binman.py b/tools/binman/binman.py
index e75a59d..d264bcd 100755
--- a/tools/binman/binman.py
+++ b/tools/binman/binman.py
@@ -34,7 +34,7 @@
     """Run the functional tests and any embedded doctests"""
     import entry_test
     import fdt_test
-    import func_test
+    import ftest
     import test
     import doctest
 
@@ -44,7 +44,7 @@
         suite.run(result)
 
     sys.argv = [sys.argv[0]]
-    for module in (func_test.TestFunctional, fdt_test.TestFdt,
+    for module in (ftest.TestFunctional, fdt_test.TestFdt,
                    entry_test.TestEntry):
         suite = unittest.TestLoader().loadTestsFromTestCase(module)
         suite.run(result)