metag: ftrace: remove the misleading comment for ftrace_dyn_arch_init

ftrace_dyn_arch_init no longer in kstop_machine, so remove the
corresponding comment.

Signed-off-by: Li Bin <huawei.libin@huawei.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
1 file changed