sysctl: ia64 Use the compat_sys_sysctl

Now that we have a generic 32bit compatibility implementation
there is no need for ia64 to implement it's own.

Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>