drm/display: fix typo

While studying the code I've bumped into a small typo within the
kernel-doc for two functions, apparently, due to copy-paste.

This commit fixes "sizo" word to be "size".

Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Fixes: b3daa5ef

 ("drm: Add helper for DP++ adaptors")
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240119102215.201474-1-oleksandr@natalenko.name