net: openvswitch: simplify the flow_hash

static u32 flow_hash(const struct sw_flow_key *key,

		     const struct sw_flow_key_range *range)

{

	int key_start = range->start;

	int key_end = range->end;

	const u32 *hash_key = (const u32 *)((const u8 *)key + key_start);

	int hash_u32s = (key_end - key_start) >> 2;

	const u32 *hash_key = (const u32 *)((const u8 *)key + range->start);

	/* Make sure number of hash bytes are multiple of u32. */

	BUILD_BUG_ON(sizeof(long) % sizeof(u32));

	int hash_u32s = range_n_bytes(range) >> 2;

	return jhash2(hash_key, hash_u32s, 0);

}