regulator: cros-ec: Fix error code in dev_err message

Show proper error code instead of 0.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Link: https://lore.kernel.org/r/20210512075824.620580-1-axel.lin@ingics.com
Signed-off-by: Mark Brown <broonie@kernel.org>