cxl/mem: Do not return error if CONFIG_CXL_MCE unset

cxl/mem: Do not return error if CONFIG_CXL_MCE unset

CONFIG_CXL_MCE depends on CONFIG_MEMORY_FAILURE, if
CONFIG_CXL_MCE is not set, devm_cxl_register_mce_notifier() will return
an -EOPNOTSUPP, it will cause cxl_mem_state_create() failure , and then
cxl pci device probing failed. In this case, it should not break cxl pci
device probing.

Add a checking in cxl_mem_state_create() to check if the returned value
of devm_cxl_register_mce_notifier() is -EOPNOTSUPP, if yes, just output
a warning log, do not let cxl_mem_state_create() return an error.

Signed-off-by: Li Ming <ming.li@zohomail.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://patch.msgid.link/20250227101848.388595-1-ming.li@zohomail.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>