remove usage of the LTE_RRC_VERSION macro
The LTE_RRC_VERSION was supposed to allow generation of different oai binaries depending on the 3GPP release. This mechanism is questionable: release n has to be compatible with n-1, so run-time tests should be used if release dependent code is necessary. Moreover, CI only check the latest release implemented by oai, and the effort to modify this cannot be supported.So At 17th of September 2019 developer meeting, it has been decided to remove usage of LTE_RRC_VERSION macro.