arm64: correct END() copy-pasteo for generic_bs_fault

PR: 256197
Reported by: Nick Reilly
MFC after: 1 week
Fixes: 95a85c125d0e67 ("Add NetBSD compatible bus_space...")
Sponsored by: The FreeBSD Foundation

(cherry picked from commit d097687b315671191b16494c938d3ceecd3eca4f)