Use over-writable parameters from the environment.
e.g.
make JESD_MODE=64B66B RX_RATE=24.75 TX_RATE=12.375 REF_CLK_RATE=375 RX_JESD_L=4 TX_JESD_L=4
make JESD_MODE=64B66B RX_RATE=16.22016 TX_RATE=16.22016 REF_CLK_RATE=245.76 RX_JESD_M=8 RX_JESD_L=2 TX_JESD_M=16 TX_JESD_L=4
make JESD_MODE=8B10B RX_JESD_L=4 RX_JESD_M=8 TX_JESD_L=4 TX_JESD_M=8