regulator: cros-ec-regulator: Add NULL test for devm_kmemdup call

Fix possible NULL pointer dereference.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Link: https://lore.kernel.org/r/20200802032509.305425-1-axel.lin@ingics.com
Signed-off-by: Mark Brown <broonie@kernel.org>
1 file changed