EDAC/xgene: Remove set but not used address local var

Fix the following gcc warning:

  drivers/edac/xgene_edac.c:1486:7: warning: variable ‘address’ set but
  not used [-Wunused-but-set-variable]
     u32 address;
         ^~~~~~~
Remove the unused macro RBERRADDR_RD while at it.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200409093259.20069-1-yanaijie@huawei.com