PCU: s/f_establish_tbf/f_pcuif_tx_rach_rx_imm_ass/g

Fix confusion: f_ms_establish_ul_tbf() vs f_establish_tbf(). The
new name precisely describes what the function does. Sending a
RACH.ind and receiving a DATA.req with RR Immediate Assignment
is just a part of the TBF establishment process.

Change-Id: I1e22b9936bf68ebcaf70cefbc57345995ebbbaed
2 files changed