fronthaul bugfixes for IF4p5 2x2 antenna configuration, testing with TM2

openair1/PHY/LTE_TRANSPORT/if4_tools.c

openair1/PHY/LTE_TRANSPORT/prach.c

openair1/PHY/LTE_TRANSPORT/transport_proto.h

openair1/PHY/LTE_UE_TRANSPORT/initial_sync.c

openair1/SCHED/prach_procedures.c

openair1/SIMULATION/RF/dac.c

openair1/SIMULATION/TOOLS/channel_sim.c

openair1/SIMULATION/TOOLS/multipath_channel.c

...TS/GENERIC-LTE-EPC/CONF/rcc.band7.tm1.if4p5.50PRB.lo.conf

targets/PROJECTS/GENERIC-LTE-EPC/CONF/rru.oaisim.conf

targets/RT/USER/lte-ru.c