syscall: Add socketpair to syscall.csv

Summary:
- This commit adds socketpair to syscall.csv

Impact:
- None

Testing:
- Tested with adb (not merged net)

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

include/sys/syscall_lookup.h

@@ -371,6 +371,7 @@ SYSCALL_LOOKUP(futimens,                   2)
   SYSCALL_LOOKUP(sendmsg,                  3)
   SYSCALL_LOOKUP(setsockopt,               5)
   SYSCALL_LOOKUP(socket,                   3)
+  SYSCALL_LOOKUP(socketpair,               4)
 #endif
 
 /* The following is defined only if CONFIG_TASK_NAME_SIZE > 0 */