x86: Enable DM RTC support for all x86 boards

Add a RTC node in the device tree to enable DM RTC support.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
(Squashed in 'x86: Fix RTC build error on ivybridge')
14 files changed