CONFIG_AR7 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

Texas Instruments AR7

configname: CONFIG_AR7

System type
└─>Texas Instruments AR7
In linux kernel since version 2.6.31 (release Date: 2009-09-09)  
Support for the Texas Instruments AR7 System-on-a-Chip
family: TNETD7100, 7200 and 7300.


is selected by
CONFIG_CPMAC