Changes

ranap_common_ran: rename ctx -> priv

This is basically commit 05bb6ad563c178de70645e815557fe225cd078b9
applied to ranap_common_ran instead of ranap_common_cn.

Rename the "ctx" argument of ranap_ran_rx_co to "priv"
as it is private user data passed to the callback.

Change-Id: I23f7f16cd7c487931226035e2616c85b75d79d08