EDAC/thunderx: Make symbols static

Make a couple of symbols static, as reported by sparse.

 [ bp: Massage. ]

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/1587624744-97240-1-git-send-email-zou_wei@huawei.com