CONFIG_PS3_VUART is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

PS3 Virtual UART support

modulename: vuart.ko

and/or

ps3-vuart.ko

configname: CONFIG_PS3_VUART

Linux Kernel Configuration
└─>PS3 Platform Options
└─>PS3 Virtual UART support
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
Include support for the PS3 Virtual UART.

This support is required for several system services
including the System Manager and AV Settings. In
general, all users will say Y.

source code: