ioctl: Rearrange members in nvme_zns_append_args

ioctl: Rearrange members in nvme_zns_append_args

Avoid any holes in the struct by rearranging the members. Also add the
attribute packed to struct definition to reduce ABI breakage.

struct nvme_zns_append_args {
        int                        args_size;            /*     0     4 */
        int                        fd;                   /*     4     4 */
        __u64 *                    result;               /*     8     8 */
        __u32                      timeout;              /*    16     4 */
        __u32                      nsid;                 /*    20     4 */
        __u64                      zslba;                /*    24     8 */
        __u16                      nlb;                  /*    32     2 */
        __u16                      control;              /*    34     2 */
        __u32                      ilbrt;                /*    36     4 */
        __u16                      lbat;                 /*    40     2 */
        __u16                      lbatm;                /*    42     2 */
        __u32                      data_len;             /*    44     4 */
        void *                     data;                 /*    48     8 */
        void *                     metadata;             /*    56     8 */
        /* --- cacheline 1 boundary (64 bytes) --- */
        __u32                      metadata_len;         /*    64     4 */

        /* size: 72, cachelines: 2, members: 15 */
        /* padding: 4 */
        /* last cacheline: 8 bytes */
} __attribute__((__aligned__(8)));

Signed-off-by: Daniel Wagner <dwagner@suse.de>