xfrm: Use xfrm_state selector for BEET input

For BEET the inner address and therefore family is stored in the
xfrm_state selector.  Use that when decapsulating an input packet
instead of incorrectly relying on a non-existent tunnel protocol.

Fixes: 5f24f41e8e ("xfrm: Remove inner/outer modes from input path")
Reported-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/xfrm/xfrm_input.c

@@ -331,11 +331,10 @@ xfrm_inner_mode_encap_remove(struct xfrm_state *x,
 {
 	switch (x->props.mode) {
 	case XFRM_MODE_BEET:
-		switch (XFRM_MODE_SKB_CB(skb)->protocol) {
-		case IPPROTO_IPIP:
-		case IPPROTO_BEETPH:
+		switch (x->sel.family) {
+		case AF_INET:
 			return xfrm4_remove_beet_encap(x, skb);
-		case IPPROTO_IPV6:
+		case AF_INET6:
 			return xfrm6_remove_beet_encap(x, skb);
 		}
 		break;