scsi: ipr: Replace 1-element arrays with flexible arrays

Replace the deprecated[1] use of a 1-element arrays in struct
ipr_hostrcb_fabric_desc and struct ipr_hostrcb64_fabric_desc with modern
flexible arrays.

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/20240711180702.work.536-kees@kernel.org


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