phy_procedures_nr_gNB.c calls pack_srs() functions to pack individual SRS "subPDUs". Correspondingly, the library depends on NFAPI_LIB. In nr_ulsim, in a later commit, we will need to unpack the SRS.indication, so remove dummy functions and implement correctly. Signed-off-by: Robert Schmidt <robert.schmidt@openairinterface.org>