scsi: pm8001: Set up tags before using them

The current code is buggy in that the tags are set up after they are needed
in pm80xx_chip_init() -> pm80xx_set_sas_protocol_timer_config().  The tag
depth is earlier read in pm80xx_chip_init() -> read_main_config_table().

Add a post init callback to do the pm80xx work which needs to be done after
reading the tags. I don't see a better way to do this.

Link: https://lore.kernel.org/r/1654879602-33497-3-git-send-email-john.garry@huawei.com


Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>