This patch fixes the AMD POGO errata on the hotplug controller where the
platform will lock up or reboot if PERR/SERR generation is enabled and a
slot is sent an enable command.  This fix disables PERR/SERR generation
before a slot is sent the enable command by first saving related
registers, turning off SERR/PERR generation, enabling the slot, then
restoring the registers.

Signed-off-by: David Keck <david.keck@amd.com>
Cc: Kristen Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>