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

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

Based on testing and recommendations by David Lechner et al. [1][2],
using = { } to initialize a structure or array is the preferred way
to do this in the kernel.

Converts memset() to = { }, thereby:
- Eliminating the risk of sizeof() mismatches.
- Simplifying the code.

[1]: https://lore.kernel.org/linux-iio/202505090942.48EBF01B@keescook/
[2]: https://lore.kernel.org/lkml/20250614151844.50524610@jic23-huawei/

Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>