audio: Fix NULL check

We already know jAudioAttributeArray is non-NULL (or else we'd
crash when dereferencing it).  We really want to check if the
contents of jAudioAttributeArray is NULL or not, so we fix this
check.

Test: TreeHugger
Change-Id: I956d99fe608f5e1b9cd0bc3e7c4075e343a6b5ab