scsi: pm8001: Move function header and supply some missing parameter descriptions

scsi: pm8001: Move function header and supply some missing parameter descriptions

Functions must follow directly after the header that documents them.

Fixes the following W=1 kernel build warning(s):

from  drivers/scsi/pm8001/pm8001_sas.c:41:
inlined from ‘pm8001_issue_ssp_tmf’ at  drivers/scsi/pm8001/pm8001_sas.c:919:2:
 drivers/scsi/pm8001/pm8001_sas.c:379: warning: Function parameter or member 'pm8001_dev' not described in 'DEV_IS_GONE'
 drivers/scsi/pm8001/pm8001_sas.c:379: warning: Excess function parameter 'task' description in 'DEV_IS_GONE'
 drivers/scsi/pm8001/pm8001_sas.c:379: warning: Excess function parameter 'num' description in 'DEV_IS_GONE'
 drivers/scsi/pm8001/pm8001_sas.c:379: warning: Excess function parameter 'gfp_flags' description in 'DEV_IS_GONE'
 drivers/scsi/pm8001/pm8001_sas.c:379: warning: Excess function parameter 'is_tmf' description in 'DEV_IS_GONE'
 drivers/scsi/pm8001/pm8001_sas.c:379: warning: Excess function parameter 'tmf' description in 'DEV_IS_GONE'
 drivers/scsi/pm8001/pm8001_sas.c:583: warning: Function parameter or member 'device_id' not described in 'pm8001_find_dev'
 drivers/scsi/pm8001/pm8001_sas.c:1000: warning: Function parameter or member 'dev' not described in 'pm8001_I_T_nexus_reset'

Link: https://lore.kernel.org/r/20200721164148.2617584-11-lee.jones@linaro.org
Cc: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>