CONFIG_NR_ONCHIP_DMA_CHANNELS is not available for thedefaultarchitecture x86.
Result is shown for architecture sh

CONFIG_NR_ONCHIP_DMA_CHANNELS (not configurable)

configname: CONFIG_NR_ONCHIP_DMA_CHANNELS

Linux Kernel Configuration
└─>DMA support
└─>NR_ONCHIP_DMA_CHANNELS
In linux kernel since version 2.6.12  
This allows you to specify the number of channels that the on-chip
DMAC supports. This will be 4 for SH7709/SH7750/SH7750S/SH7751/SH7091,
8 for SH7750R/SH7751R/SH7760, and 12 for SH7723/SH7724/SH7780/SH7785.
Default is 6.

depends
CONFIG_SH_DMA