ANDROID: Incremental fs: fix up attempt to copy structures with READ/WRITE_ONCE

READ/WRITE_ONCE are for atomic data types, not for structures.  Fix this
up by doing a memcpy to make it explicit just how messy this copy is...

This fixes a build error on 5.8-rc1, as things are more strict, odds are
it's also wrong in other kernel versions as well...

Cc: Daniel Mentz <danielmentz@google.com>
Cc: Paul Lawrence <paullawrence@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I7ecd3d05bd94c936dd5e69c63028458786f37a78