CONFIG_BCM63XX_CPU_6368 is not available for the selected architecture x86.
Result is shown for architecture mips

support 6368 CPU

configname: CONFIG_BCM63XX_CPU_6368

Linux Kernel Configuration
└─>CPU support
└─>support 6368 CPU
In linux kernel since version 3.1 (release Date: 2011-10-24)

depends
CONFIG_BCM63XX