Update VmaCallbacks to return bool

A change to libmeminfo now requires that VmaCallbacks return a bool
value. This updates the existing usage in camera_device.cc with a no-op
'return true'.

Test: n/a
Bug: 320480542
Change-Id: I1f3756a3729c90a8cef2f6159109c649e7c19b52
1 file changed