test: Rename test_fit() to test_fit_base()

The current name is uses as a root name by a few other tests, such as
test_fit_ecdsa() which makes it hard to run just this test.

Rename it to test_fit_base()

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

test/py/tests/test_fit.py

@@ -119,7 +119,7 @@ host save hostfs 0 %(loadables2_addr)x %(loadables2_out)s %(loadables2_size)x
 @pytest.mark.boardspec('sandbox')
 @pytest.mark.buildconfigspec('fit_signature')
 @pytest.mark.requiredtool('dtc')
-def test_fit(ubman):
+def test_fit_base(ubman):
     def make_fname(leaf):
         """Make a temporary filename