When backing up or restoring contents of pinned objects at suspend /
resume time we need to allocate a new object as the backup. Add a function
to facilitate copies between the two. Some data needs to be copied before
the migration context is ready for operation, so make sure we can
disable accelerated copies.

v2:
- Fix a missing return value check (Matthew Auld)
Signed-off-by: NThomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: NMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210922062527.865433-2-thomas.hellstrom@linux.intel.com