platform/chrome: cros_ec_lpc: Move host command to prepare/complete

Update cros_ec_lpc_pm_ops to call cros_ec_lpc_prepare() during PM
.prepare() and cros_ec_lpc_complete() during .complete(). This moves the
host command that the AP sends and allows the EC to log entry/exit of
AP's suspend/resume more accurately.

Reviewed-by: Raul E Rangel <rrangel@chromium.org>
Signed-off-by: Tim Van Patten <timvp@chromium.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20230515142552.1.I17cae37888be3a8683911991602f18e482e7a621@changeid