[MIPS] Wire up the timerfd_*() o32 system calls

This patch enables the system calls timerfd_create(), timerfd_settime()
and timerfd_gettime() for MIPS architecture.

Please see the following Bugzilla entry for more details:

http://bugzilla.kernel.org/show_bug.cgi?id=10038

This was tested using a Malta 4Kc board in both little-endian and
big-endian modes. The unit test program is available from the URL
above.

Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@gmail.com>

[Ralf: Added N64, N32 and O32 bits on 64-bit kernels.]
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/scall64-64.S

@@ -478,4 +478,7 @@ sys_call_table:
 	PTR	sys_ni_syscall
 	PTR	sys_eventfd
 	PTR	sys_fallocate
+	PTR	sys_timerfd_create		/* 5280 */
+	PTR	sys_timerfd_gettime
+	PTR	sys_timerfd_settime
 	.size	sys_call_table,.-sys_call_table