The C_NUM_BANKS_MEM parameter is used to configure the number of clock enable and chip select lines. Doesn't that refer to the number of ranks?
Yes, C_NUM_BANKS_MEM would have been better labeled as C_NUM_RANKS_MEM. Use C_NUM_BANKS_MEM as the number of ranks of memory connected to the memory controller.
This issue is not planned to be changed. It does not affect newer memory controllers such as the MPMC or PPC440MC_DDR2 controllers.