Tweaking workaround to use fallback with null buffer

- This case still shouldn't ever happen, but we're still
  getting crashes. It looks like the call to wrapHardwareBuffer
  will always create a hw buffer even if the graphic buffer
  is null, and the internal call to wrap the hw buffer may
  not have the flags if a null buffer is provided.

Bug: 157562905
Test: Haven't been able to reproduce
Change-Id: Ia61809a4dc53317139446d099cfa262c095d2aea
Merged-In: Ia61809a4dc53317139446d099cfa262c095d2aea