pcu_l1_if_phy: fix API function names

The functions l1if_open_pdch and l1if_close_pdch have a misleading
naming since what they actually do is opening and closing the TRX since
they return and accept a context (obj) that is valid for a whole TRX.
This also explains why the other functions accept a timeslot as
parameter in addition to the context. Let's rename those functions so
that it is clear what they do.

Change-Id: I395a60b2fba39bac4facec78989bac20f0cef0d3
---
M src/ericsson-rbs/er_ccu_if.c
M src/ericsson-rbs/er_ccu_l1_if.c
M src/osmo-bts-litecell15/lc15_l1_if.c
M src/osmo-bts-oc2g/oc2g_l1_if.c
M src/osmo-bts-sysmo/sysmo_l1_if.c
M src/osmobts_sock.c
M src/pcu_l1_if.cpp
M src/pcu_l1_if_phy.h
M tests/alloc/AllocTest.cpp
M tests/alloc/MslotTest.cpp
M tests/app_info/AppInfoTest.cpp
M tests/edge/EdgeTest.cpp
M tests/emu/pcu_emu.cpp
M tests/fn/FnTest.cpp
M tests/llc/LlcTest.cpp
M tests/ms/MsTest.cpp
M tests/tbf/TbfTest.cpp
M tests/types/TypesTest.cpp
M tests/ulc/PdchUlcTest.cpp
19 files changed, 51 insertions(+), 35 deletions(-)