parisc: Avoid using hardware single-step in kprobes

This patch changes the kprobe and kretprobe feature to use another
break instruction instead of relying on the hardware single-step
feature.
That way those kprobes now work in qemu as well, because in qemu we
don't emulate yet single-stepping.

Signed-off-by: Helge Deller <deller@gmx.de>