CONFIG_HAVE_AT91_USART5 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_HAVE_AT91_USART5 (not configurable)

configname: CONFIG_HAVE_AT91_USART5

Linux Kernel Configuration
└─>HAVE_AT91_USART5
In linux kernel since version 2.6.33 (release Date: 2010-02-24)