gw: Add NRF24L01 node_ops 'driver' skeleton
gw: Add NRF24L01 node_ops 'driver' skeleton

This patch adds the initial code to implement node_ops 'driver'
abstraction for NRF24L01. NRF24L01 is connected to the host through SPI
connection, and multiple users must be managed using 'pipes' which are
analogous to radio access code for a logical channel.

CESARBR/knot-service-source,CESARBR/knot-service-source,CESARBR/knot-service-source,CESARBR/knot-service-source,CESARBR/knot-service-source