CONFIG_DEBUG_KEYSTONE_UART0 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Kernel low-level debugging on KEYSTONE2 using UART0

configname: CONFIG_DEBUG_KEYSTONE_UART0

Kernel low-level debugging port
└─>Kernel low-level debugging on KEYSTONE2 using UART0
In linux kernel since version 3.11 (release Date: 2013-09-02)  
Say Y here if you want the debug print routines to direct
their output to UART0 serial port on KEYSTONE2 devices.