RTC: Revert UIE emulation removal

Uwe pointed out that my alarm based UIE emulation is not sufficient
to replace the older timer/polling based UIE emulation on devices
where there is no alarm irq. This causes rtc devices without alarms
to return -EINVAL to UIE ioctls. The fix is to re-instate the old
timer/polling method for devices without alarm irqs.

This patch reverts the following commits:
042620a0 - Remove UIE emulation
1daeddd5 - Cleanup removed UIE emulation declaration
b5cc8ca1

 - Remove Kconfig symbol for UIE emulation

The emulation mode will still need to be wired-in with a following
patch before it will work.

CC: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
CC: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>