CONFIG_DEBUG_UART_8250_SHIFT is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Register offset shift for the 8250 debug UART

configname: CONFIG_DEBUG_UART_8250_SHIFT

Linux Kernel Configuration
└─>Register offset shift for the 8250 debug UART
In linux kernel since version 3.12 (release Date: 2013-11-03)