EINJ: Add CXL error type support

Move CXL protocol error types from einj.c (now einj-core.c) to einj-cxl.c.
einj-cxl.c implements the necessary handling for CXL protocol error
injection and exposes an API for the CXL core to use said functionality,
while also allowing the EINJ module to be built without CXL support.
Because CXL error types targeting CXL 1.0/1.1 ports require special
handling, only allow them to be injected through the new cxl debugfs
interface (next commit) and return an error when attempting to inject
through the legacy interface.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
Link: https://lore.kernel.org/r/20240311142508.31717-3-Benjamin.Cheatham@amd.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>