Fix W=1 warnings:

cs42l42.c: In function 'cs42l42_handle_device_data':
cs42l42.c:1661:12: warning: comparison of unsigned expression >= 0 is
always true [-Wtype-limits]
 1661 |   if ((val >= CS42L42_BTN_DET_INIT_DBNCE_MIN) &&
      |            ^~
cs42l42.c:1679:12: warning: comparison of unsigned expression >= 0 is
always true [-Wtype-limits]
 1679 |   if ((val >= CS42L42_BTN_DET_EVENT_DBNCE_MIN) &&
      |            ^~
cs42l42.c:1698:23: warning: comparison of unsigned expression >= 0 is
always true [-Wtype-limits]
 1698 |    if ((thresholds[i] >= CS42L42_HS_DET_LEVEL_MIN) &&
      |                       ^~
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200701181320.80848-3-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>