siemens/mc_bdx1: Add usage of external RTC PCF8523

This mainboard contains an external RTC chip PCF8523. Enable usage of
this chip and add some initialization values to device tree.

Change-Id: I25c0a017899ee904f3aa02bdc7dcaf61dee67e3a
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/15642
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
2 files changed