[Mellanox] update buffers and align QoS to add support for DSCP remapping (for Dual-Tor on t1) for Mellanox-SN4700-O8C48

[Mellanox] update buffers and align QoS to add support for DSCP remapping (for Dual-Tor on t1) for Mellanox-SN4700-O8C48 #99