Resolve "SIGSEGV in nr-softmodem @ 100MHz on USRP"

Closes #684 (closed): Redefining NR_MAX_OFDM_SYMBOL_SIZE in openair1/PHY/defs_nr_common.h from 4096 to 8192 resolves this issue.

In earlier releases delay table was defined as and hence it was working -

c16_t ul_delay_table[2 * MAX_UL_DELAY_COMP + 1][NR_MAX_OFDM_SYMBOL_SIZE * 2]; 

In current release it is defined as

delay_table[2 * MAX_DELAY_COMP + 1][NR_MAX_OFDM_SYMBOL_SIZE];