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

TI OMAP

configname: CONFIG_ARCH_OMAP

ARM system type
└─>TI OMAP
In linux kernel since version 2.6.12  
Support for TI's OMAP platform (OMAP1 and OMAP2).

is selected by
CONFIG_DMA_OMAP

is depended by
CONFIG_ARCH_OMAP1