CONFIG_ARCH_OMAP1 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

TI OMAP1

configname: CONFIG_ARCH_OMAP1

Linux Kernel Configuration
└─>TI OMAP1
In linux kernel since version 2.6.13 (release Date: 2005-08-28)  
Support for older TI OMAP1 (omap7xx, omap15xx or omap16xx)

selects
CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
CONFIG_ARCH_OMAP
CONFIG_CLKSRC_MMIO
CONFIG_FORCE_PCI
CONFIG_GPIOLIB