scsi: sd: Do not attempt to configure discard unless LBPME is set

Commit f874d721 ("scsi: sd: Keep the discard mode stable") attempted
to address an issue where one mode of discard operation got configured
prior to the device completing full discovery.  Unfortunately this
change assumed discard was always enabled on the device.

Do not attempt to configure discard unless LBPME is enabled.

Link: https://lore.kernel.org/r/20240817005325.3319384-1-martin.petersen@oracle.com


Fixes: f874d721 ("scsi: sd: Keep the discard mode stable")
Reported-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Tested-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Tested-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>