Variable d_len_code is set to zero, but this value is never read as
it is overwritten or not used later on, hence it is a redundant
assignment and can be removed.

Clean up the following clang-analyzer warning:

sound/soc/codecs/rt286.c:728:2: warning: Value stored to 'd_len_code' is
never read [clang-analyzer-deadcode.DeadStores].
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Link: https://lore.kernel.org/r/1620298735-31708-1-git-send-email-jiapeng.chong@linux.alibaba.comSigned-off-by: Mark Brown <broonie@kernel.org>