message: [utils] use `__FILE__` in failure logs
  This commit uses `__FILE__` in failure logs instead of `__FUNCTION__`.
  It's difficult to locate the error when using `__FUNCTION__` because
  many methods are using the same name, e.g. `Init`.
diff: { \
  if ((aStatus) != 0) \
  { \
  - otbrLogEmerg("FAILED %s:%d - %s", __FUNCTION__, __LINE__, aMessage); \
  + otbrLogEmerg("FAILED %s:%d - %s", __FILE__, __LINE__, aMessage); \
  exit(-1); \
  } \
  } while (false)
  { \
  if (!(aCondition)) \
  { \
  - otbrLogEmerg("FAILED %s:%d - %s", __FUNCTION__, __LINE__, aMessage); \
  + otbrLogEmerg("FAILED %s:%d - %s", __FILE__, __LINE__, aMessage); \
  exit(-1); \
  } \
  } while (false)
  