cxl/cper: Fix non-ACPI-APEI-GHES build

If ACPI_APEI_GHES is not configured the [un]register work functions are
not properly declared.

0day notices that the cxl_cper_register_work() declaration in the
CONFIG_ACPI_APEI_GHES=n is broken, fix it to be typical nop stub.
Reported-by: kernel test robot <lkp@intel.com>
Closes: http://lore.kernel.org/r/202405012230.6kXItWen-lkp@intel.comReviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20240501-cper-fix-0day-v1-1-c0b0056eafbc@intel.comSigned-off-by: Dave Jiang <dave.jiang@intel.com>

include/linux/cxl-event.h

@@ -164,12 +164,12 @@ int cxl_cper_register_work(struct work_struct *work);
 int cxl_cper_unregister_work(struct work_struct *work);
 int cxl_cper_kfifo_get(struct cxl_cper_work_data *wd);
 #else
-static inline int cxl_cper_register_work(struct work_struct *work);
+static inline int cxl_cper_register_work(struct work_struct *work)
 {
 	return 0;
 }
 
-static inline int cxl_cper_unregister_work(struct work_struct *work);
+static inline int cxl_cper_unregister_work(struct work_struct *work)
 {
 	return 0;
 }