RISC-V: Fix PTRACE_SETREGSET bug.

In riscv_gpr_set, pass regs instead of &regs to user_regset_copyin to fix
gdb segfault.
Signed-off-by: Jim Wilson <jimw@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

arch/riscv/kernel/ptrace.c

@@ -50,7 +50,7 @@ static int riscv_gpr_set(struct task_struct *target,
 	struct pt_regs *regs;
 
 	regs = task_pt_regs(target);
-	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &regs, 0, -1);
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, regs, 0, -1);
 	return ret;
 }