kernel-netlink: Read protocol of acquire not from template

If a policy with IPComp template triggers an acquire, we get two, one for
an IPComp, one for ESP/AH SA.  However, the triggering template of the trap
policy (where we get the reqid from), will be the same in both acquires,
IPComp, which we ignore, so no acquire was actually forwarded.

src/libcharon/plugins/kernel_netlink/kernel_netlink_ipsec.c

@@ -899,9 +899,10 @@ static void process_acquire(private_kernel_netlink_ipsec_t *this,
 	size_t rtasize;
 	traffic_selector_t *src_ts, *dst_ts;
 	uint32_t reqid = 0;
-	int proto = 0;
+	uint8_t proto;
 
 	acquire = NLMSG_DATA(hdr);
+	proto = acquire->id.proto;
 	rta = XFRM_RTA(hdr, struct xfrm_user_acquire);
 	rtasize = XFRM_PAYLOAD(hdr, struct xfrm_user_acquire);
 
@@ -916,7 +917,6 @@ static void process_acquire(private_kernel_netlink_ipsec_t *this,
 			struct xfrm_user_tmpl* tmpl;
 			tmpl = (struct xfrm_user_tmpl*)RTA_DATA(rta);
 			reqid = tmpl->reqid;
-			proto = tmpl->id.proto;
 		}
 		rta = RTA_NEXT(rta, rtasize);
 	}