The current HMI event structure is an ABI and carries a version field to
accommodate future changes without affecting/rearranging current structure
members that are valid for previous versions.
The current version check "if (hmi_evt->version != OpalHMIEvt_V1)"
doesn't accomodate the fact that the version number may change in
future.
If firmware starts returning an HMI event with version > 1, this check
will fail and no HMI information will be printed on older kernels.