CONFIG_BCM63XX_CPU_3368 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

support 3368 CPU

configname: CONFIG_BCM63XX_CPU_3368

Linux Kernel Configuration
└─>CPU support
└─>support 3368 CPU
In linux kernel since version 3.10 (release Date: 2013-06-30)  

depends
CONFIG_BCM63XX