EDAC/ghes: Scan the system once on driver init

Change the hardware scanning and figuring out how many DIMMs a machine
has to a single, one-time thing which happens once on driver init. After
that scanning completes, struct ghes_hw_desc contains a representation
of the hardware which the driver can then use for later initialization.

Then, copy the DIMM information into the respective EDAC core
representation of those.

Get rid of ghes_edac_dimm_fill and use a struct dimm_info array
directly.

This way, hw detection and further driver initialization is nicely
and logically split. Further additions should all be added to
ghes_scan_system() and the hw representation extended as needed.

There should be no functionality change resulting from this patch.

Signed-off-by: Borislav Petkov <bp@suse.de>