elf: Rename load_segments() and module failure

Rename this function to make it clear that it only reads loadable
segments. Also update the error for missing module to better match the
message emitted by Python.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Suggested-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
diff --git a/tools/binman/elf_test.py b/tools/binman/elf_test.py
index d401b5b..02bc108 100644
--- a/tools/binman/elf_test.py
+++ b/tools/binman/elf_test.py
@@ -243,7 +243,7 @@
             fname = self.ElfTestFile('embed_data')
             with self.assertRaises(ValueError) as e:
                 elf.GetSymbolFileOffset(fname, ['embed_start', 'embed_end'])
-            self.assertIn('Python elftools package is not available',
+            self.assertIn("Python: No module named 'elftools'",
                       str(e.exception))
         finally:
             elf.ELF_TOOLS = old_val
@@ -257,31 +257,31 @@
         offset = elf.GetSymbolFileOffset(fname, ['missing_sym'])
         self.assertEqual({}, offset)
 
-    def test_read_segments(self):
-        """Test for read_segments()"""
+    def test_read_loadable_segments(self):
+        """Test for read_loadable_segments()"""
         if not elf.ELF_TOOLS:
             self.skipTest('Python elftools not available')
         fname = self.ElfTestFile('embed_data')
-        segments, entry = elf.read_segments(tools.read_file(fname))
+        segments, entry = elf.read_loadable_segments(tools.read_file(fname))
 
     def test_read_segments_fail(self):
-        """Test for read_segments() without elftools"""
+        """Test for read_loadable_segments() without elftools"""
         try:
             old_val = elf.ELF_TOOLS
             elf.ELF_TOOLS = False
             fname = self.ElfTestFile('embed_data')
             with self.assertRaises(ValueError) as e:
-                elf.read_segments(tools.read_file(fname))
-            self.assertIn('Python elftools package is not available',
+                elf.read_loadable_segments(tools.read_file(fname))
+            self.assertIn("Python: No module named 'elftools'",
                           str(e.exception))
         finally:
             elf.ELF_TOOLS = old_val
 
     def test_read_segments_bad_data(self):
-        """Test for read_segments() with an invalid ELF file"""
+        """Test for read_loadable_segments() with an invalid ELF file"""
         fname = self.ElfTestFile('embed_data')
         with self.assertRaises(ValueError) as e:
-            elf.read_segments(tools.get_bytes(100, 100))
+            elf.read_loadable_segments(tools.get_bytes(100, 100))
         self.assertIn('Magic number does not match', str(e.exception))
 
     def test_get_file_offset(self):