scsi: pm8001: Fix memory leak in pm8001_chip_fw_flash_update_req()

In pm8001_chip_fw_flash_update_build(), if
pm8001_chip_fw_flash_update_build() fails, the struct fw_control_ex
allocated must be freed.

Link: https://lore.kernel.org/r/20220220031810.738362-23-damien.lemoal@opensource.wdc.com
Reviewed-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>