kallsyms: Add more debug output for selftest

kallsyms: Add more debug output for selftest

While debugging a recent kallsyms_selftest failure[1], I needed more
details on what specifically was failing. This adds those details for
each failure state that is checked.

[1] https://lore.kernel.org/all/202308232200.1c932a90-oliver.sang@intel.com/

Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Yonghong Song <yhs@meta.com>
Cc: "Erhard F." <erhard_f@mailbox.org>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Cc: kernel test robot <oliver.sang@intel.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>