binman: Correct the error message for invalid path

At present this message references -o for output file. But binman uses -f
now. Fix it.
Signed-off-by: NSimon Glass <sjg@chromium.org>

tools/binman/control.py

@@ -138,9 +138,9 @@ def ExtractEntries(image_fname, output_fname, outdir, entry_paths,
     # Output an entry to a single file, as a special case
     if output_fname:
         if not entry_paths:
-            raise ValueError('Must specify an entry path to write with -o')
+            raise ValueError('Must specify an entry path to write with -f')
         if len(entry_paths) != 1:
-            raise ValueError('Must specify exactly one entry path to write with -o')
+            raise ValueError('Must specify exactly one entry path to write with -f')
         entry = image.FindEntryPath(entry_paths[0])
         data = entry.ReadData(decomp)
         tools.WriteFile(output_fname, data)

tools/binman/ftest.py

@@ -2683,7 +2683,7 @@ class TestFunctional(unittest.TestCase):
         image_fname = tools.GetOutputFilename('image.bin')
         with self.assertRaises(ValueError) as e:
             control.ExtractEntries(image_fname, 'fname', None, [])
-        self.assertIn('Must specify an entry path to write with -o',
+        self.assertIn('Must specify an entry path to write with -f',
                       str(e.exception))
 
     def testExtractTooManyEntryPaths(self):
@@ -2693,7 +2693,7 @@ class TestFunctional(unittest.TestCase):
         image_fname = tools.GetOutputFilename('image.bin')
         with self.assertRaises(ValueError) as e:
             control.ExtractEntries(image_fname, 'fname', None, ['a', 'b'])
-        self.assertIn('Must specify exactly one entry path to write with -o',
+        self.assertIn('Must specify exactly one entry path to write with -f',
                       str(e.exception))
 
     def testPackAlignSection(self):