kerndat: Handle non-root mode when checking uffd

When criu is run as user it fails and exits because of kerndat_uffd() returning -1.
This, in turn, happens after uffd = syscall(SYS_userfaultfd, flags); which only works
for root.

In the change it ignores the permission error and proceeds further just like it's done
for e.g. pagemap checking.

Signed-off-by: Nithin Jaikar J <jaikar006@gmail.com>

criu/kerndat.c

@@ -919,7 +919,10 @@ static int kerndat_uffd(void)
 	if (uffd < 0) {
 		if (uffd == -ENOSYS)
 			return 0;
-
+		if (uffd == -EPERM) {
+			pr_info("Lazy pages are disabled\n");
+			return 0;
+		}
 		pr_err("Lazy pages are not available\n");
 		return -1;
 	}