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

Support for Graphics workaround

configname: CONFIG_DMAR_GFX_WA

Linux Kernel Configuration for x86
└─>Bus options (PCI etc.)
└─>Support for Graphics workaround
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
Current Graphics drivers tend to use physical address
for DMA and avoid using DMA APIs. Setting this config
option permits the IOMMU driver to set a unity map for
all the OS-visible memory. Hence the driver can continue
to use physical addresses for DMA.