Initialize array pointer to nullptr am: 80019eb5c1 am: 8145973fe7 am: 50b71aaf5d am: 39c17dc7cd am: f49abcdd7e

Original change: https://android-review.googlesource.com/c/platform/system/keymaster/+/1778106

Change-Id: I8e5db2679f79f3c15e79c04f4d550d8a93fc961d