drivers: ieee802154: add MCR20A driver

Add driver and configuration for the MCR20A 802.15.4
transceiver.

Jira: ZEP-1429

Change-Id: I0b17b688220a47c2f0e5cde269064bbd0dec824a
Signed-off-by: Johann Fischer <j.fischer@phytec.de>
6 files changed