CONFIG_PPC_A2_DD2 is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc
default or selected kernelversion does not have config value CONFIG_PPC_A2_DD2.
Result is shown for kernelversion 6.2.5

Support for DD2 based A2/WSP systems

configname: CONFIG_PPC_A2_DD2

Linux Kernel Configuration
└─>Support for DD2 based A2/WSP systems
In linux kernel since version 3 (release Date: 2011-07-21)  
depends
CONFIG_PPC_A2