AVRCP: Proper null check for SET_ATTRIBUTE_VALUES

SET_ATTRIBUTE_VALUES case there is check if
device is null then it is returning without
sending SendSetPlayerAppRsp, so audio intent
is not handle for player app setting changed.
Put SET_ATTRIBUTE_VALUES under proper null check.

CRs-Fixed: 2327707
Change-Id: Ia0e55fd99de5a3c01a33f94f801800928beaa911
1 file changed