ASoC: SOF: Kconfig: Make IPC_FLOOD_TEST depend on SND_SOC_SOF

ASoC: SOF: Kconfig: Make IPC_FLOOD_TEST depend on SND_SOC_SOF

Make sure that the IPC_FLOOD client can not be built in when SND_SOC_SOF is
built as module.

Fixes: 6e9548cdb30e5 ("ASoC: SOF: Convert the generic IPC flood test into SOF client")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220823121554.4255-2-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>