scsi: scsi_dh_alua: Prevent duplicate pg info print in alua_rtpg()

scsi: scsi_dh_alua: Prevent duplicate pg info print in alua_rtpg()

Due to the frequency that alua_rtpg() is called, the path group info print
within can print the same info multiple times in the logs, subsequent
prints adding no new information or value.

To reproduce:

    # modprobe scsi_debug vpd_use_hostno=0
    # systemctl start multipathd.service

To fix, check stored values, only printing at alua attach/activate and if
any of the values change.

Link: https://lore.kernel.org/r/20210331181656.5046-1-jpittman@redhat.com
Reviewed-by: David Jeffery <djeffery@redhat.com>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: John Pittman <jpittman@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>