ASoC: qcom: fix unsigned int bitwidth compared to less than zero

The check for an error return from the call to snd_pcm_format_width
is never true as the unsigned int bitwidth can never be less than
zero. Fix this by making bitwidth an int.

Fixes: 7cb37b7b

 ("ASoC: qcom: Add support for lpass hdmi driver")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20201028115112.109017-1-colin.king@canonical.com
Signed-off-by: Mark Brown <broonie@kernel.org>