platform: nordic_nrf: Set BL2 and secondary partition if not defined

As the platform config is loaded before the default config BL2 has to
be set explicitly if not present.

Change-Id: I918b2523e234eb7ed2761c36a13b0226f0731e53
Author: Markus Swarowsky <markus.swarowsky@nordicsemi.no>
Signed-off-by: Markus Swarowsky <markus.swarowsky@nordicsemi.no>
2 files changed