Update VmaCallbacks to return bool

A change to libmeminfo now requires that VmaCallbacks return a bool
value. This updates the existing usages in frameworks/base with
effectively no-op 'return true's.

Test: n/a
Bug: 320480542
Change-Id: I9a2894b9beec8d4a13887a1c9444f2ebc5036343
2 files changed