scsi: bfa: Replace one-element array with flexible-array member in struct fc_rscn_pl_s

One-element and zero-length arrays are deprecated. So, replace one-element
array in struct fc_rscn_pl_s with flexible-array member.

This results in no differences in binary output.

Link: https://github.com/KSPP/linux/issues/339
Signed-off-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/ZN0VTpDBOSVHGayb@work
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>