[GCC4] fix warning in include/linux/atalk.h

[GCC4] fix warning in include/linux/atalk.h

This patch fixes this warning with gcc 4 :

In file included from /usr/src/git/linux-2.4/include/net/sock.h:90,
                 from /usr/src/git/linux-2.4/include/net/ip.h:39,
                 from /usr/src/git/linux-2.4/include/net/checksum.h:31,
                 from /usr/src/git/linux-2.4/include/linux/raid/md.h:35,
                 from check.c:21:

/usr/src/git/linux-2.4/include/linux/atalk.h:140: warning: 'packed' attribute ignored for field of type '__u8[5u]'
/usr/src/git/linux-2.4/include/linux/atalk.h:141: warning: 'packed' attribute ignored for field of type '__u8'
/usr/src/git/linux-2.4/include/linux/atalk.h:143: warning: 'packed' attribute ignored for field of type '__u8'
/usr/src/git/linux-2.4/include/linux/atalk.h:144: warning: 'packed' attribute ignored for field of type '__u8[5u]'
/usr/src/git/linux-2.4/include/linux/atalk.h:145: warning: 'packed' attribute ignored for field of type '__u8'
/usr/src/git/linux-2.4/include/linux/atalk.h:147: warning: 'packed' attribute ignored for field of type '__u8'