Add Imprecise flag for memory access fault

KFD may not be  able to provide the precise VM fault address and status.
This flag will indicate whether the event data has the fault details

Change-Id: I15ffd5c25f555003c6450cc0700efb769418f76b

include/linux/kfd_ioctl.h

@@ -222,7 +222,7 @@ struct kfd_memory_exception_failure {
 	bool NotPresent;  /* Page not present or supervisor privilege */
 	bool ReadOnly;  /* Write access to a read-only page */
 	bool NoExecute;  /* Execute access to a page marked NX */
-	bool pad;
+	bool imprecise;  /* Can't determine the  exact fault address */
 };
 
 /* memory exception data*/