syscall: remove unused accept on linux/loong64

accept is no longer used on Linux since CL 346849 changed Accept to use
accept4 only.

This follows CL 386415 which already removed accept on all other Linux
platforms before the linux/loong64 port was submitted.

For #45964

Change-Id: I26945ff780e71174a0b0c2f5313c4bc1e1cbf786
Reviewed-on: https://go-review.googlesource.com/c/go/+/410737
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

src/syscall/syscall_linux_loong64.go

@@ -101,7 +101,6 @@ func Lstat(path string, stat *Stat_t) (err error) {
 //sys	Statfs(path string, buf *Statfs_t) (err error)
 //sys	SyncFileRange(fd int, off int64, n int64, flags int) (err error)
 //sys	Truncate(path string, length int64) (err error)
-//sys	accept(s int, rsa *RawSockaddrAny, addrlen *_Socklen) (fd int, err error)
 //sys	accept4(s int, rsa *RawSockaddrAny, addrlen *_Socklen, flags int) (fd int, err error)
 //sys	bind(s int, addr unsafe.Pointer, addrlen _Socklen) (err error)
 //sys	connect(s int, addr unsafe.Pointer, addrlen _Socklen) (err error)