binman: Tweak elf tests for a toolchain change

Some newer toolchains do not create a symbol for the .ucode section that
this test relies on. Update the test to use the symbol that is explicitly
created, instead.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/elf_test.py b/tools/binman/elf_test.py
index ac69a95..f727258 100644
--- a/tools/binman/elf_test.py
+++ b/tools/binman/elf_test.py
@@ -99,17 +99,17 @@
         """Test that we can obtain a symbol from the ELF file"""
         fname = self.ElfTestFile('u_boot_ucode_ptr')
         syms = elf.GetSymbols(fname, [])
-        self.assertIn('.ucode', syms)
+        self.assertIn('_dt_ucode_base_size', syms)
 
     def testRegexSymbols(self):
         """Test that we can obtain from the ELF file by regular expression"""
         fname = self.ElfTestFile('u_boot_ucode_ptr')
         syms = elf.GetSymbols(fname, ['ucode'])
-        self.assertIn('.ucode', syms)
+        self.assertIn('_dt_ucode_base_size', syms)
         syms = elf.GetSymbols(fname, ['missing'])
-        self.assertNotIn('.ucode', syms)
+        self.assertNotIn('_dt_ucode_base_size', syms)
         syms = elf.GetSymbols(fname, ['missing', 'ucode'])
-        self.assertIn('.ucode', syms)
+        self.assertIn('_dt_ucode_base_size', syms)
 
     def testMissingFile(self):
         """Test that a missing file is detected"""