ASoC: max98090: remove superflous check for 'micbias'

In max98090_probe(), code checks for micbias being out of range. The
'micbias' variable in unsigned and checked against M98090_MBVSEL_2V2 which
is zero, so remove this check.

sound/soc/codecs/max98090.c: In function ‘max98090_probe’:
sound/soc/codecs/max98090.c:2459:2: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
  } else if (micbias < M98090_MBVSEL_2V2 || micbias > M98090_MBVSEL_2V8) {

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>