Fix W=1 warning:

sound/soc//tegra/tegra20_das.c:101:11: warning:
comparison of unsigned expression >= 0 is always true [-Wtype-limits]
  101 |  if ((reg >= TEGRA20_DAS_DAP_CTRL_SEL) &&
      |           ^~
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://lore.kernel.org/r/20200707190612.97799-5-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>