charge_state_v2: return correct host command error codes
charge_state_v2: return correct host command error codes

Return host command error codes for EC_CMD_CHARGE_CONTROL instead
of returning the result of EC functions which typically return
element from enum ec_error_list, which is a different error list.

BUG=chrome-os-partner:37171
BRANCH=samus
TEST=make -j buildall

Change-Id: Ia13cc8a2f747ddeafdc059c6e575dcc2f5b20b8d
Signed-off-by: Alec Berg <1a4429eeda29095a12e19a73405f80f5b7f37a63@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/254721
Reviewed-by: Duncan Laurie <70662b43bc1a20b57ded72a2b08be88dd0da4841@chromium.org>
Reviewed-by: Bill Richardson <129945214b1d548d8e49b6c29c43094f8c78057f@chromium.org>
(cherry picked from commit 1dccd0450e7ba7cfa4d61fbd0ddac4c910b5b763)
Reviewed-on: https://chromium-review.googlesource.com/254830

thehobn/ec,thehobn/ec,thehobn/ec,thehobn/ec