drm/rockchip: cdn-dp: Clean up a few logged messages

Clean up a few logged messages, which were previously worded as rather
incomplete sentences separated by periods.  This was both a bit unreadable
and grammatically incorrect, so convert them into partial sentences separated
(or connected) by semicolons, together with some wording improvements.

Signed-off-by: Dragan Simic <dsimic@manjaro.org>
Reviewed-by: Andy Yan <andyshrk@163.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/92db74a313547c087cc71059428698c4ec37a9ae.1720048818.git.dsimic@manjaro.org