MIPS: N64: Wire getdents64(2)

As a relatively new ABI, N64 only had getdents syscall while other modern
architectures have getdents64.

This was noticed when Python 3.3 shifted to the latter one for aarch64.

[ralf@linux-mips.org: The history of getdents64 is a little complicated.
Commit 1a1d77dd589de5a567fa95e36aa6999c704ceca4 [Merge with 2.4.0-test7.]
added N64 getdents(2) to arch/mips64/kernel/scall_64.S as syscall 5213,
then dropped again in 578720675c44e54e8aa7c68f6dce59ed37ce3d3b [Overhaul
of the 64-bit syscall interface.  Now heritage free.] for 2.5.18 in 2002.]
Signed-off-by: NAron Xu <aron@debian.org>
Acked-by: NDavid Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5285/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/include/uapi/asm/unistd.h

@@ -694,16 +694,17 @@
 #define __NR_process_vm_writev		(__NR_Linux + 305)
 #define __NR_kcmp			(__NR_Linux + 306)
 #define __NR_finit_module		(__NR_Linux + 307)
+#define __NR_getdents64			(__NR_Linux + 308)
 
 /*
  * Offset of the last Linux 64-bit flavoured syscall
  */
-#define __NR_Linux_syscalls		307
+#define __NR_Linux_syscalls		308
 
 #endif /* _MIPS_SIM == _MIPS_SIM_ABI64 */
 
 #define __NR_64_Linux			5000
-#define __NR_64_Linux_syscalls		307
+#define __NR_64_Linux_syscalls		308
 
 #if _MIPS_SIM == _MIPS_SIM_NABI32
 

arch/mips/kernel/scall64-64.S

@@ -423,4 +423,5 @@ sys_call_table:
 	PTR	sys_process_vm_writev		/* 5305 */
 	PTR	sys_kcmp
 	PTR	sys_finit_module
+	PTR	sys_getdents64
 	.size	sys_call_table,.-sys_call_table