PCI: hotplug: Remove obsolete sgi_hotplug TODO notes

Commit c7532b6 ("PCI/hotplug: remove the sgi_hotplug driver") deleted
the driver.

Remove the remaining TODO notes as well.

Link: https://lore.kernel.org/r/26784ee39fbb3fbd0fe96508158d74419018e6ad.1714762038.git.namcao@linutronix.de
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Author: covanam

drivers/pci/hotplug/TODO

@@ -49,14 +49,6 @@ ibmphp:
 
 * Returned code from pci_hp_add_bridge() is not checked.
 
-sgi_hotplug:
-
-* Several functions access the pci_slot member in struct hotplug_slot even
-  though pci_hotplug.h declares it private.  See sn_hp_destroy() for an
-  example.  Either the pci_slot member should no longer be declared private
-  or sgi_hotplug should store a pointer to it in struct slot.  Probably the
-  former.
-
 shpchp:
 
 * There is only a single implementation of struct hpc_ops.  Can the struct be