runtime/internal/syscall: use ABIInternal for Syscall6 on loong64

runtime/internal/syscall: use ABIInternal for Syscall6 on loong64

Updates #40724

Co-authored-by: Xiaolin Zhao <zhaoxiaolin@loongson.cn>
Change-Id: Ifcc2de35a797fd987a10f564206b14b54d736d1d
Reviewed-on: https://go-review.googlesource.com/c/go/+/521789
Auto-Submit: David Chase <drchase@google.com>
Reviewed-by: Meidan Li <limeidan@loongson.cn>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>