ARM: compat: remove KERNEL_DS usage in sys_oabi_epoll_ctl()

We no longer need to switch to KERNEL_DS mode in sys_oabi_epoll_ctl()
as we can use do_epoll_ctl() to avoid the additional copy.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

arch/arm/kernel/sys_oabi-compat.c

@@ -253,20 +253,15 @@ asmlinkage long sys_oabi_epoll_ctl(int epfd, int op, int fd,
 {
 	struct oabi_epoll_event user;
 	struct epoll_event kernel;
-	mm_segment_t fs;
-	long ret;
 
-	if (op == EPOLL_CTL_DEL)
-		return sys_epoll_ctl(epfd, op, fd, NULL);
-	if (copy_from_user(&user, event, sizeof(user)))
+	if (ep_op_has_event(op) &&
+	    copy_from_user(&user, event, sizeof(user)))
 		return -EFAULT;
+
 	kernel.events = user.events;
 	kernel.data   = user.data;
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-	ret = sys_epoll_ctl(epfd, op, fd, &kernel);
-	set_fs(fs);
-	return ret;
+
+	return do_epoll_ctl(epfd, op, fd, &kernel, false);
 }
 
 asmlinkage long sys_oabi_epoll_wait(int epfd,