net: sched: Use FIELD_SIZEOF directly instead of reimplementing its function

FIELD_SIZEOF is defined as a macro to calculate the specified value. Therefore,
We prefer to use the macro rather than calculating its value.
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_flower.c

@@ -993,7 +993,7 @@ static int fl_init_mask_hashtable(struct fl_flow_mask *mask)
 }
 
 #define FL_KEY_MEMBER_OFFSET(member) offsetof(struct fl_flow_key, member)
-#define FL_KEY_MEMBER_SIZE(member) (sizeof(((struct fl_flow_key *) 0)->member))
+#define FL_KEY_MEMBER_SIZE(member) FIELD_SIZEOF(struct fl_flow_key, member)
 
 #define FL_KEY_IS_MASKED(mask, member)						\
 	memchr_inv(((char *)mask) + FL_KEY_MEMBER_OFFSET(member),		\