Documentation-getdelays: Apply a recommendation from "checkpatch.pl" in main()

The script "checkpatch.pl" pointed out that assignments should usually
not be performed within condition checks.
Thus move the assignment for the variable "nl_sd" to a separate statement.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/accounting/getdelays.c

@@ -375,7 +375,8 @@ int main(int argc, char *argv[])
 		}
 	}
 
-	if ((nl_sd = create_nl_socket(NETLINK_GENERIC)) < 0)
+	nl_sd = create_nl_socket(NETLINK_GENERIC);
+	if (nl_sd < 0)
 		err(1, "error creating Netlink socket\n");