CONFIG_ARCH_OMAP2PLUS is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_ARCH_OMAP2PLUS (not configurable)

modulename: omap_prm.ko

configname: CONFIG_ARCH_OMAP2PLUS

Linux Kernel Configuration
└─>TI OMAP/AM/DM/DRA Family
└─>ARCH_OMAP2PLUS
In linux kernel since version 2.6.34 (release Date: 2010-05-16)  
Systems based on OMAP2, OMAP3, OMAP4 or OMAP5

source code:
drivers/soc/ti/omap_prm.c