module: power_domain: fix trace resources
Created by: etienne-lms
Fixes power_domain.c that macro used FWK_LOG_LEVEL_ERR whereas error trace level macro is FWK_LOG_LEVEL_ERROR and to define local get_state_name() helper function when at least error trace level is enabled.
Signed-off-by: Etienne Carriere etienne.carriere@linaro.org