Fix memory leak in Bluetooth AVRCP JNI

When rebasing change-id I3941793f9843abf4afa5ffbee40d1d01c118b29b
later change eb8bf9eb in AOSP,
a memory leak fix was removed by accident. This patch re-enables
the memory leak fix.

Bug: 26383160
Change-Id: I70fd2ea00f6135803f92aad3adda9ce38f47cc32
Signed-off-by: Casper Bonde <c.bonde@samsung.com>
(cherry picked from commit 6477a1c7)