Fix for Null-dereference read in ixheaacd_init_sbr

Header decode is done with AOT 2 (AAC-LC profile),
but due to corrupted nature of input file AOT is read
as 42 (USAC profile) after few memory/table initializations.

As fix, modified the check to prevent an attempt
to change AOT in mid file.

Bug: 160389683
Test: poc in bug

Change-Id: Id95aa74b0833321b29b602d97b14c5a5580ef7fc
1 file changed