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

Generic OMAP2+ board

modulename: board-generic.ko

configname: CONFIG_MACH_OMAP_GENERIC

Linux Kernel Configuration
└─>TI OMAP2/3/4 Specific Features
└─>Generic OMAP2+ board
In linux kernel since version 2.6.12  
Support for generic TI OMAP2+ boards using Flattened Device Tree.
More information at
source code:
arch/arm/mach-omap2/board-generic.c