CONFIG_DEBUG_VEXPRESS_UART0_RS1 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Use PL011 UART0 at 0x1c090000 (RS1 complaint tiles)

configname: CONFIG_DEBUG_VEXPRESS_UART0_RS1

Kernel low-level debugging port
└─>Use PL011 UART0 at 0x1c090000 (RS1 complaint tiles)
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This option selects UART0 at 0x1c090000. This applies to most
of the tiles using the RS1 memory map, including all new A-class
core tiles, FPGA-based SMMs and software models.