LDPC T2 card: fix and doc update
- update of the documentation: usage with latest SW, higher DPDK version
- fix of buffer overflow detected in nr_ulsch_decoding.c: set buffer size to max E (number of encoded bits) - max E is 32768- for BG2, MCS0
- fix of HARQ codeblock ID out of range (error reported by the T2 card): modification of the harq input/output offset calculation
- offset is calculated using ulsch_id (index in the global array of running harq processes) and r (index of CB in TB)