CONFIG_DEBUG_UART_PL01X is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_DEBUG_UART_PL01X (not configurable)

configname: CONFIG_DEBUG_UART_PL01X

Linux Kernel Configuration
└─>Kernel hacking
└─>DEBUG_UART_PL01X
In linux kernel since version 3.10 (release Date: 2013-06-30)