subdev/clk: fix repeated words in comments

 Delete the redundant word 'at'.

Signed-off-by: wangjianli <wangjianli@cdjrlc.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220821143038.46589-1-wangjianli@cdjrlc.com