cxl/pmem: Add "Unlock" security command support

Create callback function to support the nvdimm_security_ops() ->unlock()
callback. Translate the operation to send "Unlock" security command for CXL
mem device.

When the mem device is unlocked, cpu_cache_invalidate_memregion() is called
in order to invalidate all CPU caches before attempting to access the mem
device.

See CXL rev3.0 spec section 8.2.9.8.6.4 for reference.

Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/166983614167.2734609.15124543712487741176.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>