audio: add USAGE_UNKNOWN to mediaActive condition

1.If an app play media but the usage of attributes is unknown, musicActivecheck should be started.
2.USAGE_UNKNOWN default value is MEDIA.
3.Otherwise, the mMusicActiveMs will not increase for safe volume when above safe volume.
4.Users listen to music until 20 hours later but the volume does not drop.

Change-Id: I5f84b2c6376b283376d65d398e880a8716c98f59
Signed-off-by: liutianxiang <liutianxiang@xiaomi.com>