CONFIG_ATARI_SCC_DMA is not available for the default architecture x86.
Result is shown for architecture m68k
default or selected kernelversion does not have config value CONFIG_ATARI_SCC_DMA.
Result is shown for kernelversion 5.5.18

Atari SCC serial DMA support


Linux/68k Kernel Configuration
└─> Character devices
└─> Atari SCC serial DMA support

This enables DMA support for receiving data on channel A of the SCC.
If you have a TT you may say Y here and read
drivers/char/atari_SCC.README. All other users should say N here,
because only the TT has SCC-DMA, even if your machine keeps claiming
so at boot time.