media: mediatek: vcodec: use = { } instead of memset()

[Markus Elfring]

>> …
>>> This patch converts …
>> See also once more:
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.16#n94
> I don't think your point is a problem here. …

Will any contributors care more for the usage of imperative mood
also according to improved change descriptions?

Regards,
Markus