Fix for Null-dereference read in ixheaacd_init_sbr am: a741e1d5de am: 154faafaa9 am: 969c6ce482 am: 21a96efe69

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

Change-Id: I4dd3fda28fd7d061c6efca479683eb0896a04c4e