[XFRM]: unexport xfrm_state_mtu

This patch removes the unused EXPORT_SYMBOL(xfrm_state_mtu).

Signed-off-by: Adrian Bunk <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/xfrm/xfrm_state.c

···
 	return res;
 }
 
-EXPORT_SYMBOL(xfrm_state_mtu);
-
 int xfrm_init_state(struct xfrm_state *x)
 {
 	struct xfrm_state_afinfo *afinfo;