net, uapi: remove inclusion of arpa/inet.h

In include/uapi/linux/tipc_config.h, there's a comment that it includes
arpa/inet.h for ntohs; but ntohs is not defined in any UAPI header. For
now, reuse the definitions from include/linux/byteorder/generic.h, since
the various conversion functions do exist in UAPI headers:
include/uapi/linux/byteorder/big_endian.h
include/uapi/linux/byteorder/little_endian.h

We would like to get to the point where we can build UAPI header tests
with -nostdinc, meaning that kernel UAPI headers should not have a
circular dependency on libc headers.

Link: https://android-review.googlesource.com/c/platform/bionic/+/2048127
Suggested-by: Jakub Kicinski <[e-mail]>
Signed-off-by: Nick Desaulniers <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/uapi/linux/tipc_config.h

···
 #include <linux/tipc.h>
 #include <asm/byteorder.h>
 
-#ifndef __KERNEL__
-#include <arpa/inet.h> /* for ntohs etc. */
-#endif
-
 /*
  * Configuration
  *
···
 	 */
 
 	return (space >= TLV_SPACE(0)) &&
-		(ntohs(((struct tlv_desc *)tlv)->tlv_len) <= space);
+		(__be16_to_cpu(((struct tlv_desc *)tlv)->tlv_len) <= space);
 }
 
 static inline int TLV_CHECK(const void *tlv, __u16 space, __u16 exp_type)
 {
 	return TLV_OK(tlv, space) &&
-		(ntohs(((struct tlv_desc *)tlv)->tlv_type) == exp_type);
+		(__be16_to_cpu(((struct tlv_desc *)tlv)->tlv_type) == exp_type);
 }
 
 static inline int TLV_GET_LEN(struct tlv_desc *tlv)
 {
-	return ntohs(tlv->tlv_len);
+	return __be16_to_cpu(tlv->tlv_len);
 }
 
 static inline void TLV_SET_LEN(struct tlv_desc *tlv, __u16 len)
 {
-	tlv->tlv_len = htons(len);
+	tlv->tlv_len = __cpu_to_be16(len);
 }
 
 static inline int TLV_CHECK_TYPE(struct tlv_desc *tlv,  __u16 type)
 {
-	return (ntohs(tlv->tlv_type) == type);
+	return (__be16_to_cpu(tlv->tlv_type) == type);
 }
 
 static inline void TLV_SET_TYPE(struct tlv_desc *tlv, __u16 type)
 {
-	tlv->tlv_type = htons(type);
+	tlv->tlv_type = __cpu_to_be16(type);
 }
 
 static inline int TLV_SET(void *tlv, __u16 type, void *data, __u16 len)
···
 
 	tlv_len = TLV_LENGTH(len);
 	tlv_ptr = (struct tlv_desc *)tlv;
-	tlv_ptr->tlv_type = htons(type);
-	tlv_ptr->tlv_len  = htons(tlv_len);
+	tlv_ptr->tlv_type = __cpu_to_be16(type);
+	tlv_ptr->tlv_len  = __cpu_to_be16(tlv_len);
 	if (len && data) {
 		memcpy(TLV_DATA(tlv_ptr), data, len);
 		memset((char *)TLV_DATA(tlv_ptr) + len, 0, TLV_SPACE(len) - tlv_len);
···
 
 static inline void TLV_LIST_STEP(struct tlv_list_desc *list)
 {
-	__u16 tlv_space = TLV_ALIGN(ntohs(list->tlv_ptr->tlv_len));
+	__u16 tlv_space = TLV_ALIGN(__be16_to_cpu(list->tlv_ptr->tlv_len));
 
 	list->tlv_ptr = (struct tlv_desc *)((char *)list->tlv_ptr + tlv_space);
 	list->tlv_space -= tlv_space;
···
 
 	msg_len = TCM_LENGTH(data_len);
 	tcm_hdr = (struct tipc_cfg_msg_hdr *)msg;
-	tcm_hdr->tcm_len   = htonl(msg_len);
-	tcm_hdr->tcm_type  = htons(cmd);
-	tcm_hdr->tcm_flags = htons(flags);
+	tcm_hdr->tcm_len   = __cpu_to_be32(msg_len);
+	tcm_hdr->tcm_type  = __cpu_to_be16(cmd);
+	tcm_hdr->tcm_flags = __cpu_to_be16(flags);
 	if (data_len && data) {
 		memcpy(TCM_DATA(msg), data, data_len);
 		memset((char *)TCM_DATA(msg) + data_len, 0, TCM_SPACE(data_len) - msg_len);