efi/cper, cxl: Remove cxl_err.h

While going to create include/linux/cxl.h for some cross-subsystem CXL
definitions I noticed that include/linux/cxl_err.h was already present.
That header has no reason to be global, and it duplicates the RAS
Capability Structure definitions in drivers/cxl/cxl.h. A follow-on patch
can consider unifying the CXL native error tracing with the CPER error
printing.

Also fixed up the spec reference as the latest released spec is v3.0.

Cc: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

efi/cper, cxl: Decode CXL Error Log

Print the CXL Error Log field as found in CXL Protocol Error Section.

The CXL RAS Capability structure will be reused by OS First Handling
and the duplication/appropriate placement will be addressed eventually.

Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

efi/cper, cxl: Decode CXL Protocol Error Section

Add support for decoding CXL Protocol Error Section as defined in UEFI 2.10
Section N.2.13.

Do the section decoding in a new cper_cxl.c file. This new file will be
used in the future for more CXL CPERs decode support. Add this to the
existing UEFI_CPER config.

Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>