CONFIG_ARCH_LPC32XX_UART6_SELECT is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_ARCH_LPC32XX_UART6_SELECT.
Result is shown for kernelversion 6.2.5

Add support for standard UART6

configname: CONFIG_ARCH_LPC32XX_UART6_SELECT

Linux Kernel Configuration
└─>Individual UART enable selections
└─>Add support for standard UART6
In linux kernel since version 2.6.36 (release Date: 2010-10-20)  
Adds support for standard UART 6 when the 8250 serial support
is enabled.