docs: pdfdocs: Fix typo in CJK-language specific font settings

There were typos in the fallback definitions of dummy LaTeX macros
for systems without CJK fonts.
They cause build errors in "make pdfdocs" on such systems.
Fix them.

Fixes: e291ff6f ("docs: pdfdocs: Add CJK-language-specific font settings")
Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Link: https://lore.kernel.org/r/ad7615a5-f8fa-2bc3-de6b-7ed49d458964@gmail.com


Signed-off-by: Jonathan Corbet <corbet@lwn.net>