paride: fix potential information leak in pg_read()

Smatch has a new check for Rosenberg type information leaks where structs
are copied to the user with uninitialized stack data in them.  i In this
case, the pg_write_hdr struct has a hole in it.

struct pg_write_hdr {
        char                       magic;                /*     0     1 */
        char                       func;                 /*     1     1 */
        /* XXX 2 bytes hole, try to pack */
        int                        dlen;                 /*     4     4 */

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Tim Waugh <tim@cyberelk.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>