sysctl: parisc Use the compat_sys_sysctl

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

Cc: Thibaut Varene <T-Bone@parisc-linux.org>
Acked-by: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>