CONFIG_DEBUG_VEXPRESS_UART0_DETECT is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Autodetect UART0 on Versatile Express Cortex-A core tiles

configname: CONFIG_DEBUG_VEXPRESS_UART0_DETECT

Kernel low-level debugging port
└─>Autodetect UART0 on Versatile Express Cortex-A core tiles
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This option enables a simple heuristic which tries to determine
the motherboard's memory map variant (original or RS1) and then
choose the relevant UART0 base address.

Note that this will only work with standard A-class core tiles,
and may fail with non-standard SMM or custom software models.