binman: elf: Add more debugging to LookupAndWriteSymbols()

When symbol-writing does not appear to work, it can sometimes be hard to
figure out what is going on. Add some more debugging to help.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/elf.py b/tools/binman/elf.py
index 2ecc95f..a469405 100644
--- a/tools/binman/elf.py
+++ b/tools/binman/elf.py
@@ -275,7 +275,7 @@
         return 0
     base = syms.get(base_sym)
     if not base and not is_elf:
-        tout.debug('LookupAndWriteSymbols: no base')
+        tout.debug(f'LookupAndWriteSymbols: no base: elf_fname={elf_fname}, base_sym={base_sym}, is_elf={is_elf}')
         return 0
     base_addr = 0 if is_elf else base.address
     count = 0