scsi: qedi: Fix host removal with running sessions

qedi_clear_session_ctx() could race with the in-kernel or userspace driven
recovery/removal and we could access a NULL conn or do a double free.

We should be using iscsi_host_remove() to start the removal process from
the driver. It will start the in-kernel recovery and notify userspace that
the driver's scsi_hosts are being removed. iscsid will then drive the
session removal like is done when the logout command is run. When the
sessions are removed, iscsi_host_remove() will return so qedi can finish
knowing there are no running sessions and no new sessions will be allowed.

This also fixes an issue where we check for a NULL conn after already
accessing it introduced in commit 27e98628 ("scsi: iscsi: Drop suspend
calls from ep_disconnect") by just removing the function completely.

Link: https://lore.kernel.org/r/20210609192709.5094-1-michael.christie@oracle.com


Fixes: 27e98628 ("scsi: iscsi: Drop suspend calls from ep_disconnect")
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>