l10n: ko: fix typos found by git-po-helper
When checking typos in file "po/ko.po", "git-po-helper" reports lots of
false positives because there are no spaces between ASCII and Korean
characters. After applied commit adee197 "(dict: add smudge table for
Korean language, 2021-11-11)" of "git-l10n/git-po-helper" to suppress
these false positives, some easy-to-fix typos are found and fixed.
Signed-off-by: Jiang Xin <worldhello.net@gmail.com>