Fix for Null-dereference read in ixheaacd_init_sbr am: a741e1d5de am: 154faafaa9

Original change: https://android-review.googlesource.com/c/platform/external/libxaac/+/1425114

Change-Id: I4ec39bc76cd0353172b5dba2167591c3f8d6553a