xfs: remove unused event xfs_ioctl_clone

xfs: remove unused event xfs_ioctl_clone

The trace event xfs_ioctl_clone was added but never used. As trace events
can take up to 5K of memory in text and meta data regardless if they are
used or not, remove the unused trace event.

Fixes: 53aa1c34f4eb ("xfs: define tracepoints for reflink activities")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>