riscv: ptrace: Remove duplicate operation

The TIF_SYSCALL_TRACE is controlled by a common code, see
kernel/ptrace.c and include/linux/thread_info.h.

clear_task_syscall_work(child, SYSCALL_TRACE);

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230222033021.983168-3-guoren@kernel.org


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>