Revert "rt,ntp: Move call to schedule_delayed_work() to helper thread"

I've been looking at this in v3.10-RT where it got in. The patch
description says

|The ntp code for notify_cmos_timer() is called from a hard interrupt
|context.

I see only one caller of ntp_notify_cmos_timer() and that is
do_adjtimex() after "raw_spin_unlock_irqrestore()".
I see a few callers of do_adjtimex() which is SYS_adjtimex() (+compat)
and posix_clock_realtime_adj() which in turn is called by
SYS_clock_adjtime().

Reverting the patch.

Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>