nvproxy: support NV2080_CTRL_CMD_PERF_GET_GPUMON_PERFMON_UTIL_SAMPLES_V2

This control command is used by NVML to sample GPU utilization (e.g.
nvmlDeviceGetProcessUtilization(), used by GPU monitoring tools like
DCGM). The V2 params struct embeds all samples inline and contains no
pointers, so it can be proxied as a simple control command.