cxl/mbox: Fix CEL logic for poison and security commands

The following debug output was observed while testing CXL

cxl_core:cxl_walk_cel:721: cxl_mock_mem cxl_mem.0: Opcode 0x4300 unsupported by driver

opcode 0x4300 (Get Poison) is supported by the driver and the mock
device supports it.  The logic should be checking that the opcode is
both not poison and not security.

Fix the logic to allow poison and security commands.

Fixes: ad64f595 ("cxl/memdev: Only show sanitize sysfs files when supported")
Cc: <stable@vger.kernel.org>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20230903-cxl-cel-fix-v1-1-e260c9467be3@intel.com


[cleanup cxl_walk_cel() to centralized "enabled" checks]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>