buddy: Avoid nullptr dereference in debugging code
buddy: Avoid nullptr dereference in debugging code

No debug bitmap is allocated for the maximum order, so don't try to
use it when freeing a maximum order block.

bowlofstew/sv6,aclements/sv6,bowlofstew/sv6,aclements/sv6,aclements/sv6,bowlofstew/sv6,bowlofstew/sv6,aclements/sv6,bowlofstew/sv6,aclements/sv6