signal/sh: Remove tsk parameter from force_sig_info_fault

The force_sig_info_fault function is always called with tsk == current.
Make that explicit by removing the tsk parameter.

This also makes it clear that the sh force_sig_info_fault passes
current into force_sig_fault.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>