ASoC: rt1011: remove redundant test

ASoC: rt1011: remove redundant test

cppcheck warning:

sound/soc/codecs/rt1011.c:1994:6: style: Condition 'tx_slotnum' is
always true [knownConditionTrueFalse]
 if (tx_slotnum)
     ^
sound/soc/codecs/rt1011.c:1895:24: note: Assuming that condition
'!tx_slotnum' is not redundant
 if (tx_slotnum > 2 || !tx_slotnum) {
                       ^
sound/soc/codecs/rt1011.c:1994:6: note: Condition 'tx_slotnum' is
always true
if (tx_slotnum)
     ^

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210302212527.55158-3-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>