[XFRM]: fix sparse gfp nocast warnings

Fix implicit nocast warnings in xfrm code:
net/xfrm/xfrm_policy.c:232:47: warning: implicit cast to nocast type

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index fda737d..c6a0d34 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -225,7 +225,7 @@
  * SPD calls.
  */
 
-struct xfrm_policy *xfrm_policy_alloc(int gfp)
+struct xfrm_policy *xfrm_policy_alloc(unsigned int __nocast gfp)
 {
 	struct xfrm_policy *policy;