syscall: remove FreeBSD 11 and below 64bit inode compatibility shims

Update #53280

Change-Id: Iaa7c0cf5dbefaa8e14c2de499f99755911c17672
Reviewed-on: https://go-review.googlesource.com/c/go/+/411596


Reviewed-by: Meng Zhuo <mzh@golangcn.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Yuval Pavel Zholkover <paulzhol@gmail.com>
Reviewed-by: Dmitri Goutnik <dgoutnik@gmail.com>