Release DrmManagerClient resources

Call release for DrmManagerClient to avoid resource leaks

Introduced by following commit (5d143ad4a8f...),
"Media scanner support for FL(Forward Lock) DRM file types"

https://android-review.googlesource.com/#/c/91081/

Change-Id: Ic3c458579f4e99b3b072a2e13362d1996b982589
Signed-off-by: houst0nn <houstonn@gmail.com>