CONFIG_ARCH_OMAP is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

TI OMAP

modulename: gpio-omap.ko

configname: CONFIG_ARCH_OMAP

ARM system type
└─>TI OMAP
In linux kernel since version 2.6.12  
Support for TI's OMAP platform (OMAP1/2/3/4).

source code: