[MIPS] Fix the MIPS getsid system call

Change-Id: I30a27941125bccb35d73a572a729ecf7dd555389
Signed-off-by: Chris Dearman <chris@mips.com>
diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index 58e0ac1..2973caa 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -62,7 +62,7 @@
 int     getgroups:getgroups(int, gid_t *)      -1,-1,80
 pid_t   getpgid(pid_t)             132
 pid_t   getppid()                  64
-pid_t   getsid(pid_t)              147
+pid_t   getsid(pid_t)              147,147,151
 pid_t   setsid()                   66
 int     setgid:setgid32(gid_t)     214,214,-1
 int     setgid:setgid(gid_t)       -1,-1,46