EDAC/ghes: Remove unused members of struct ghes_edac_pvt, rename it to ghes_pvt

The struct members list and ghes of struct ghes_edac_pvt are unused,
remove them. On that occasion, rename it to the shorter name struct
ghes_pvt.

Signed-off-by: Robert Richter <rrichter@marvell.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200519104443.15673-2-rrichter@marvell.com