added lte-enb.c which extracts all enb-specific code from lte-softmodem. corrects merge from develop branch in dlsch_modulations.c. removal of HW-specific code in lte-softmodem.c

Conflicts:
	openair1/PHY/LTE_ESTIMATION/lte_dl_mbsfn_channel_estimation.c
	openair1/PHY/TOOLS/lte_dfts.c
	openair1/SIMULATION/LTE_PHY/dlsim.c

added fixes to build on odroid/xu4 platform

changes on bugfix-48-L1L2Signaling to build for odroid platform

the branch has been tested to build on x86 platform
- builds for eNB
- can do attach
- can ping external servers

On odroid,
- builds correctly
- eNB fails to come up due to late samples (same as parent branch)


See merge request !31

Add the PCO so that MME allocates the IP address
accordingly. The protocol ID known as "IP address
allocation via NAS signalling" is assigned.

Otherwise, the OAI UE will always has IP address
set to 0.0.0.0

This has tested with OAI eNB with S1 interface using
OAI EPC.

Reference:
http://www.sharetechnote.com/html/Handbook_LTE_ProtocolConfigurationOption.html

This patch is merged with Cedric's patch and tested.
Signed-off-by: Chun-Yeow Yeoh <yeow@tmrnd.com.my>
Signed-off-by: Cedric Roux <Cedric.Roux@eurecom.fr>

Merge branch 'bugfix-48-L1L2signaling' of https://gitlab.eurecom.fr/oai/openairinterface5g into bugfix-48-L1L2signaling

usrp_lib: setting master clock rate to 30.72 and filter to 20MHz for all cases to improve noise figure and channel response