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

TI OMAP1

configname: CONFIG_ARCH_OMAP1

ARM system type
└─>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_OMAP
CONFIG_CLKSRC_MMIO
CONFIG_GENERIC_IRQ_CHIP
CONFIG_GENERIC_IRQ_MULTI_HANDLER
CONFIG_GPIOLIB
CONFIG_HAVE_LEGACY_CLK
CONFIG_IRQ_DOMAIN
CONFIG_NEED_MACH_IO_H
CONFIG_NEED_MACH_MEMORY_H
CONFIG_SPARSE_IRQ

depends
CONFIG_MMU