compat: Cleanup in_compat_syscall() callers

Now that in_compat_syscall() is consistent on all architectures and does
not longer report true on native i686, the workarounds (ifdeffery and
helpers) can be removed.

Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-efi@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: https://lkml.kernel.org/r/20181012134253.23266-3-dima@arista.com

net/xfrm/xfrm_state.c

@@ -2077,10 +2077,8 @@ int xfrm_user_policy(struct sock *sk, int optname, u8 __user *optval, int optlen
 	struct xfrm_mgr *km;
 	struct xfrm_policy *pol = NULL;
 
-#ifdef CONFIG_COMPAT
 	if (in_compat_syscall())
 		return -EOPNOTSUPP;
-#endif
 
 	if (!optval && !optlen) {
 		xfrm_sk_policy_insert(sk, XFRM_POLICY_IN, NULL);

net/xfrm/xfrm_user.c

@@ -2621,10 +2621,8 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 	const struct xfrm_link *link;
 	int type, err;
 
-#ifdef CONFIG_COMPAT
 	if (in_compat_syscall())
 		return -EOPNOTSUPP;
-#endif
 
 	type = nlh->nlmsg_type;
 	if (type > XFRM_MSG_MAX)