EDAC/thunderx: Make symbol lmc_dfs_ents static

Symbol 'lmc_dfs_ents' is not used outside of thunderx_edac.c, so
make it static:

  drivers/edac/thunderx_edac.c:457:22: warning:
   symbol 'lmc_dfs_ents' was not declared. Should it be static?

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Robert Richter <rrichter@marvell.com>
Link: https://lkml.kernel.org/r/20200714142308.46612-1-weiyongjun1@huawei.com