ghes: add the needed hooks for EDAC error report

In order to allow reporting errors via EDAC, add hooks for:

1) register an EDAC driver;
2) unregister an EDAC driver;
3) report errors via EDAC.

As the EDAC driver will need to access the ghes structure, adds it
as one of the parameters for ghes_do_proc.

Acked-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>