AVRCP: Fix unexpected index out of bounds exception

On function checkIndexOutofBounds(),
if endItem value equals to the MediaItem list,
then there will be 'IndexOutOfBoundsException'.
As sub list end value is endItem + 1,
endItem shall be smaller value than list size.

Bug: 64137660
Test: Code compiles
Change-Id: I6d2dc705451cf1f515c8fbfd4ba24ac49dc4271d
(cherry picked from commit 38506165)