PCI/AER: Replace PCIEAER_CXL symbol with CXL_RAS

PCI/AER: Replace PCIEAER_CXL symbol with CXL_RAS

One of the primary reasons for the CXL driver to exist is to perform error
handling. If both PCIEAER and CXL are enabled then light up CXL error
handling as well. Now that all RAS handling is moved under the CXL_RAS
symbol, drop the previous PCIEAER_CXL symbol.

Reviewed-by: Terry Bowman <terry.bowman@amd.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/20260114182055.46029-14-terry.bowman@amd.com
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>