scsi: message: fusion: struct _CONFIG_PAGE_IOC_4: Replace 1-element array with flexible array

Replace the deprecated[1] use of a 1-element array in struct
_CONFIG_PAGE_IOC_4 with a modern flexible array.

Additionally add __counted_by annotation since SEP is only ever accessed
after updating ACtiveSEP:

lsi/mpi_cnfg.h:    IOC_4_SEP                   SEP[] __counted_by(ActiveSEP);  /* 08h */
mptsas.c:        ii = IOCPage4Ptr->ActiveSEP++;
mptsas.c:        IOCPage4Ptr->SEP[ii].SEPTargetID = id;
mptsas.c:        IOCPage4Ptr->SEP[ii].SEPBus = channel;

No binary differences are present after this conversion.

Link: https://github.com/KSPP/linux/issues/79

 [1]
Signed-off-by: Kees Cook <kees@kernel.org>
Link: https://lore.kernel.org/r/20240711172821.123936-6-kees@kernel.org


Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>