ASoC: codecs: lpass-va-macro: remove some dead code

The "decimator" variable is in the 0-7 range and it's unsigned so there
is no need to check for negative values.

Fixes: 908e6b1d ("ASoC: codecs: lpass-va-macro: Add support to VA Macro")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/X8c5gjZO7YN/CFsq@mwanda


Signed-off-by: Mark Brown <broonie@kernel.org>