scsi: mpt3sas: Use flexible arrays when obviously possible

scsi: mpt3sas: Use flexible arrays when obviously possible

These terminal 1-length variable arrays can be directly converted into C99
flexible array members without any binary changes.

In most cases, they belong to unused structs, or to structs used only by
unused code. The remaining few coincidentally have their sizes calculated
in roundabout ways that do not depend on the sizeof() their structs.

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Seo <james@equiv.tech>
Link: https://lore.kernel.org/r/20230806170604.16143-2-james@equiv.tech
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>