drm/amd/pp: Remove meanless return value check in RV

In send_message_to_smu helper functions,
Print out the error code for debug if smu failed to response.

The helper functions always return true, so no need to
check their return value.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>