Revert "EDAC/amd64: Support more than two controllers for chip select handling"

This reverts commit 0a227af5.

Unfortunately, this commit caused wrong detection of chip select sizes
on some F17h client machines:

  --- 00-rc6+     2019-02-14 14:28:03.126622904 +0100
  +++ 01-rc4+     2019-04-14 21:06:16.060614790 +0200
   EDAC amd64: MC: 0:     0MB 1:     0MB
  -EDAC amd64: MC: 2: 16383MB 3: 16383MB
  +EDAC amd64: MC: 2:     0MB 3: 2097151MB
   EDAC amd64: MC: 4:     0MB 5:     0MB
   EDAC amd64: MC: 6:     0MB 7:     0MB
   EDAC MC: UMC1 chip selects:
   EDAC amd64: MC: 0:     0MB 1:     0MB
  -EDAC amd64: MC: 2: 16383MB 3: 16383MB
  +EDAC amd64: MC: 2:     0MB 3: 2097151MB
   EDAC amd64: MC: 4:     0MB 5:     0MB
   EDAC amd64: MC: 6:     0MB 7:     0M

Revert it for now until it has been solved properly.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Yazen Ghannam <yazen.ghannam@amd.com>