MIPS: N32: Fix signalfd4 syscall entry point

This needs to use the compat entry point or it's going to fail on big
endian systems.

Noticed by Al Viro.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/scall64-n32.S

@@ -397,7 +397,7 @@ EXPORT(sysn32_call_table)
 	PTR	sys_timerfd_create
 	PTR	compat_sys_timerfd_gettime	/* 6285 */
 	PTR	compat_sys_timerfd_settime
-	PTR	sys_signalfd4
+	PTR	compat_sys_signalfd4
 	PTR	sys_eventfd2
 	PTR	sys_epoll_create1
 	PTR	sys_dup3			/* 6290 */