media: venus: Refactor struct hfi_uncompressed_format_supported

plane_info is not a typical array, the data is not contiguous:
pinfo = (void *)pinfo + sizeof(*constr) * num_planes +
	2 * sizeof(u32);

Replace the single element array with a single element field.

This fixes the following cocci warning:
drivers/media/platform/qcom/venus/hfi_helper.h:1009:36-46: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays

)

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Acked-by: Vikash Garodia <quic_vgarodia@quicinc.com>
Signed-off-by: Stanimir Varbanov <stanimir.k.varbanov@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>