commit 0e0cd9ea upstream.

The memory allocated for chip is not freed anywhere.
Convert to use devm_kzalloc to fix the memory leak.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>