EDAC: Raise the maximum number of memory controllers

We observe an oops in the skx_edac module during boot:

  EDAC MC0: Giving out device to module skx_edac controller Skylake Socket#0 IMC#0
  EDAC MC1: Giving out device to module skx_edac controller Skylake Socket#0 IMC#1
  EDAC MC2: Giving out device to module skx_edac controller Skylake Socket#1 IMC#0
  ...
  EDAC MC13: Giving out device to module skx_edac controller Skylake Socket#0 IMC#1
  EDAC MC14: Giving out device to module skx_edac controller Skylake Socket#1 IMC#0
  EDAC MC15: Giving out device to module skx_edac controller Skylake Socket#1 IMC#1
  Too many memory controllers: 16
  EDAC MC: Removed device 0 for skx_edac Skylake Socket#0 IMC#0

We observe there are two memory controllers per socket, with a limit
of 16. Raise the maximum number of memory controllers from 16 to 2 *
MAX_NUMNODES (1024).

[ bp: This is just a band-aid fix until we've sorted out the whole issue
  with the bus_type association and handling in EDAC and can get rid of
  this arbitrary limit. ]

Signed-off-by: Justin Ernst <justin.ernst@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Russ Anderson <russ.anderson@hpe.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-edac@vger.kernel.org
Link: https://lkml.kernel.org/r/20180925143449.284634-1-justin.ernst@hpe.com