rtc: snvs: add Freescale rtc-snvs driver

Add an RTC driver for Freescale Secure Non-Volatile Storage (SNVS)
Low Power (LP) RTC.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Kim Phillips <kim.phillips@freescale.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/devicetree/bindings/rtc/snvs-rtc.txt

@@ -0,0 +1 @@
+See Documentation/devicetree/bindings/crypto/fsl-sec4.txt for details.