kernel: debug: fix typo issue

change 'regster' to 'register'.

Signed-off-by: wengjianfeng <wengjianfeng@yulong.com>
Link: https://lore.kernel.org/r/20210203081034.9004-1-samirweng1979@163.com


Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>