staging: media: meson: vdec: use min() for comparison and assignment

Use of standard min() helper macro is preferred over using ternary
operator for logical evaluation and value assignment. This issue is
identified by coccicheck using the minmax.cocci file.

Signed-off-by: Deepak R Varma <drv@mailo.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>