ASoC: dapm: Fix kcontrol path list corruption

When calling krealloc for the kcontrol data the items in the path list that
point back to the head of the list will now point to freed memory, which causes
the list to become corrupted. To fix this, instead of resizing the whole data
struct, only resize the widget list.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>