nr pdcp: first draft of NIA2 integrity

This code has not been tested with a COTS UE. We need SRB1/2 (so we need SA)
to test.

The activation of security and integrity for SRB1 will need more code
(new functions) because it happens after some time, not at creation time
of the PDCP entity and there is no way to do this with current code.

openair2/UTIL/OSA/osa_defs.h

@@ -48,7 +48,8 @@ typedef enum {
   NAS_INT_ALG = 0x02,
   RRC_ENC_ALG = 0x03,
   RRC_INT_ALG = 0x04,
-  UP_ENC_ALG  = 0x05
+  UP_ENC_ALG  = 0x05,
+  UP_INT_ALG  = 0x06
 } algorithm_type_dist_t;
 
 //int derive_keNB(const uint8_t kasme[32], const uint32_t nas_count, uint8_t **keNB);