media: venus: Convert one-element-arrays to flex-arrays

This structures are not used, and have a single element array at the end
of them.

This fix the following cocci warnings:
drivers/media/platform/qcom/venus/hfi_helper.h:764:5-15: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
drivers/media/platform/qcom/venus/hfi_helper.h:1041:5-15: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
drivers/media/platform/qcom/venus/hfi_helper.h:1088:39-51: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
drivers/media/platform/qcom/venus/hfi_helper.h:1093:5-22: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
drivers/media/platform/qcom/venus/hfi_helper.h:1144:4-8: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
drivers/media/platform/qcom/venus/hfi_helper.h:1239:4-8: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
drivers/media/platform/qcom/venus/hfi_helper.h:1272:4-13: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
drivers/media/platform/qcom/venus/hfi_cmds.h:85:5-16: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
drivers/media/platform/qcom/venus/hfi_cmds.h:180:5-9: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
drivers/media/platform/qcom/venus/hfi_cmds.h:189:5-9: 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>
Signed-off-by: Stanimir Varbanov <stanimir.k.varbanov@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>