scsi: sd: Remove the stream_status member from scsi_stream_status_header

scsi: sd: Remove the stream_status member from scsi_stream_status_header

Having a variable length array at the end of scsi_stream_status_header
only causes problems.  Remove it and switch sd_is_perm_stream(), which is
the only place that currently uses it, to use the scsi_stream_status
directly following it in the local buf structure.

Besides being a much better data structure design, this also avoids a
-Wflex-array-member-not-at-end warning.

Reported-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250505060640.3398500-1-hch@lst.de
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>