eNB TDD mode Segmentation FAult

There is a segmentation fault at eNB start-up that prevent run it

Version of OAI eNB : v1B0.4

frequency : each run

configuration : see issue #27

backtrace from gdb

got sync (eNB_thread_single) Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7fffce43b700 (LWP 26645)] trx_usrp_read (device=<optimized out>, ptimestamp=0x7ffff00c8020, buff=0x7fffce43ae10, nsamps=7680, cc=1) at /tmp/oai_develop1B_tdd/openairinterface5g/targets/ARCH/USRP/USERSPACE/LIB/usrp_lib.cpp:270 270 ((__m256i *)buff[i])[j] = _mm256_srai_epi16(buff_tmp[i][j],4);