default or selected kernelversion does not have config value CONFIG_BLK_DEV_IDEDMA_PMAC.
Result is shown for kernelversion 5.3.7

PowerMac IDE DMA support

configname: CONFIG_BLK_DEV_IDEDMA_PMAC

Linux Kernel Configuration
└─>Device Drivers
└─>ATA/ATAPI/MFM/RLL support
└─>PowerMac IDE DMA support
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
This option allows the driver for the on-board IDE controller on
Power Macintoshes and PowerBooks to use DMA (direct memory access)
to transfer data to and from memory. Saying Y is safe and improves
performance.