scsi: megaraid_sas: struct MR_HOST_DEVICE_LIST: Replace 1-element array with flexible array

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

One binary difference appears in megasas_host_device_list_query():

        struct MR_HOST_DEVICE_LIST *ci;
	...
        ci = instance->host_device_list_buf;
	...
        memset(ci, 0, sizeof(*ci));

The memset() clears only the non-flexible array fields. Looking at the rest
of the function, this appears to be fine: firmware is using this region to
communicate with the kernel, so it likely never made sense to clear the
first MR_HOST_DEVICE_LIST_ENTRY.

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

 [1]
Signed-off-by: Kees Cook <kees@kernel.org>
Link: https://lore.kernel.org/r/20240711155841.work.839-kees@kernel.org


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