ASoC: topology: Fix a signedness bug in soc_tplg_dapm_widget_create()

The "template.id" variable is an enum and in this context GCC will
treat it as an unsigned int so it can never be less than zero.

Fixes: 8a978234 ("ASoC: topology: Add topology core")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20190925110624.GR3264@mwanda


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