ARM: 6604/1: Gemini: add platform support for Gemini RTC

adds rtc support for all Gemini SoC boards
nas4220b, rut1xx, wbd111, wbd222

Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>