net ax25: Fix the build when sysctl support is disabled.

Randy Dunlap <rdunlap@xenotime.net> reported:

> On 04/23/2012 12:07 AM, Stephen Rothwell wrote:
>
>> Hi all,
>>
>> Changes since 20120420:
>
>
> include/net/ax25.h:447:75: error: expected ';' before '}' token
>
> static inline int ax25_register_dev_sysctl(ax25_dev *ax25_dev) { return 0 };
> static inline void ax25_unregister_dev_sysctl(ax25_dev *ax25_dev) {};
>
> First function:  move ';' inside braces.
> Second function:  drop the ';'.

Put the semicolons where it makes sense.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: David S. Miller <davem@davemloft.net>